Network Working Group P. Resnick, Ed.
Request for Comments: 5322 Qualcomm Incorporated
Obsoletes: 2822 October 2008
Updates: 4021
Category: Standards Track
Network Working Group P. Resnick, Ed.
Request for Comments: 5322 Qualcomm Incorporated
Obsoletes: 2822 October 2008
Updates: 4021
Category: Standards Track
Internet Message Format
互联网信息格式
Status of This Memo
关于下段备忘
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Abstract
摘要
This document specifies the Internet Message Format (IMF), a syntax for text messages that are sent between computer users, within the framework of "electronic mail" messages. This specification is a revision of Request For Comments (RFC) 2822, which itself superseded Request For Comments (RFC) 822, "Standard for the Format of ARPA Internet Text Messages", updating it to reflect current practice and incorporating incremental changes that were specified in other RFCs.
本文件规定了互联网信息格式（IMF），即在“电子邮件”信息框架内，计算机用户之间发送的文本信息的语法。本规范是对征求意见书（RFC）2822的修订，其本身取代了征求意见书（RFC）822，“ARPA互联网文本消息格式标准”，对其进行了更新，以反映当前实践，并纳入了其他RFC中规定的增量变更。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Notational Conventions . . . . . . . . . . . . . . . . . . 5
1.2.1. Requirements Notation . . . . . . . . . . . . . . . . 5
1.2.2. Syntactic Notation . . . . . . . . . . . . . . . . . . 5
1.2.3. Structure of This Document . . . . . . . . . . . . . . 5
2. Lexical Analysis of Messages . . . . . . . . . . . . . . . . . 6
2.1. General Description . . . . . . . . . . . . . . . . . . . 6
2.1.1. Line Length Limits . . . . . . . . . . . . . . . . . . 7
2.2. Header Fields . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1. Unstructured Header Field Bodies . . . . . . . . . . . 8
2.2.2. Structured Header Field Bodies . . . . . . . . . . . . 8
2.2.3. Long Header Fields . . . . . . . . . . . . . . . . . . 8
2.3. Body . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Lexical Tokens . . . . . . . . . . . . . . . . . . . . . . 10
3.2.1. Quoted characters . . . . . . . . . . . . . . . . . . 10
3.2.2. Folding White Space and Comments . . . . . . . . . . . 11
3.2.3. Atom . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2.4. Quoted Strings . . . . . . . . . . . . . . . . . . . . 13
3.2.5. Miscellaneous Tokens . . . . . . . . . . . . . . . . . 14
3.3. Date and Time Specification . . . . . . . . . . . . . . . 14
3.4. Address Specification . . . . . . . . . . . . . . . . . . 16
3.4.1. Addr-Spec Specification . . . . . . . . . . . . . . . 17
3.5. Overall Message Syntax . . . . . . . . . . . . . . . . . . 18
3.6. Field Definitions . . . . . . . . . . . . . . . . . . . . 19
3.6.1. The Origination Date Field . . . . . . . . . . . . . . 22
3.6.2. Originator Fields . . . . . . . . . . . . . . . . . . 22
3.6.3. Destination Address Fields . . . . . . . . . . . . . . 23
3.6.4. Identification Fields . . . . . . . . . . . . . . . . 25
3.6.5. Informational Fields . . . . . . . . . . . . . . . . . 27
3.6.6. Resent Fields . . . . . . . . . . . . . . . . . . . . 28
3.6.7. Trace Fields . . . . . . . . . . . . . . . . . . . . . 30
3.6.8. Optional Fields . . . . . . . . . . . . . . . . . . . 30
4. Obsolete Syntax . . . . . . . . . . . . . . . . . . . . . . . 31
4.1. Miscellaneous Obsolete Tokens . . . . . . . . . . . . . . 32
4.2. Obsolete Folding White Space . . . . . . . . . . . . . . . 33
4.3. Obsolete Date and Time . . . . . . . . . . . . . . . . . . 33
4.4. Obsolete Addressing . . . . . . . . . . . . . . . . . . . 35
4.5. Obsolete Header Fields . . . . . . . . . . . . . . . . . . 35
4.5.1. Obsolete Origination Date Field . . . . . . . . . . . 36
4.5.2. Obsolete Originator Fields . . . . . . . . . . . . . . 36
4.5.3. Obsolete Destination Address Fields . . . . . . . . . 37
4.5.4. Obsolete Identification Fields . . . . . . . . . . . . 37
4.5.5. Obsolete Informational Fields . . . . . . . . . . . . 37
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Notational Conventions . . . . . . . . . . . . . . . . . . 5
1.2.1. Requirements Notation . . . . . . . . . . . . . . . . 5
1.2.2. Syntactic Notation . . . . . . . . . . . . . . . . . . 5
1.2.3. Structure of This Document . . . . . . . . . . . . . . 5
2. Lexical Analysis of Messages . . . . . . . . . . . . . . . . . 6
2.1. General Description . . . . . . . . . . . . . . . . . . . 6
2.1.1. Line Length Limits . . . . . . . . . . . . . . . . . . 7
2.2. Header Fields . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1. Unstructured Header Field Bodies . . . . . . . . . . . 8
2.2.2. Structured Header Field Bodies . . . . . . . . . . . . 8
2.2.3. Long Header Fields . . . . . . . . . . . . . . . . . . 8
2.3. Body . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Lexical Tokens . . . . . . . . . . . . . . . . . . . . . . 10
3.2.1. Quoted characters . . . . . . . . . . . . . . . . . . 10
3.2.2. Folding White Space and Comments . . . . . . . . . . . 11
3.2.3. Atom . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2.4. Quoted Strings . . . . . . . . . . . . . . . . . . . . 13
3.2.5. Miscellaneous Tokens . . . . . . . . . . . . . . . . . 14
3.3. Date and Time Specification . . . . . . . . . . . . . . . 14
3.4. Address Specification . . . . . . . . . . . . . . . . . . 16
3.4.1. Addr-Spec Specification . . . . . . . . . . . . . . . 17
3.5. Overall Message Syntax . . . . . . . . . . . . . . . . . . 18
3.6. Field Definitions . . . . . . . . . . . . . . . . . . . . 19
3.6.1. The Origination Date Field . . . . . . . . . . . . . . 22
3.6.2. Originator Fields . . . . . . . . . . . . . . . . . . 22
3.6.3. Destination Address Fields . . . . . . . . . . . . . . 23
3.6.4. Identification Fields . . . . . . . . . . . . . . . . 25
3.6.5. Informational Fields . . . . . . . . . . . . . . . . . 27
3.6.6. Resent Fields . . . . . . . . . . . . . . . . . . . . 28
3.6.7. Trace Fields . . . . . . . . . . . . . . . . . . . . . 30
3.6.8. Optional Fields . . . . . . . . . . . . . . . . . . . 30
4. Obsolete Syntax . . . . . . . . . . . . . . . . . . . . . . . 31
4.1. Miscellaneous Obsolete Tokens . . . . . . . . . . . . . . 32
4.2. Obsolete Folding White Space . . . . . . . . . . . . . . . 33
4.3. Obsolete Date and Time . . . . . . . . . . . . . . . . . . 33
4.4. Obsolete Addressing . . . . . . . . . . . . . . . . . . . 35
4.5. Obsolete Header Fields . . . . . . . . . . . . . . . . . . 35
4.5.1. Obsolete Origination Date Field . . . . . . . . . . . 36
4.5.2. Obsolete Originator Fields . . . . . . . . . . . . . . 36
4.5.3. Obsolete Destination Address Fields . . . . . . . . . 37
4.5.4. Obsolete Identification Fields . . . . . . . . . . . . 37
4.5.5. Obsolete Informational Fields . . . . . . . . . . . . 37
4.5.6. Obsolete Resent Fields . . . . . . . . . . . . . . . . 38
4.5.7. Obsolete Trace Fields . . . . . . . . . . . . . . . . 38
4.5.8. Obsolete optional fields . . . . . . . . . . . . . . . 38
5. Security Considerations . . . . . . . . . . . . . . . . . . . 38
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
Appendix A. Example Messages . . . . . . . . . . . . . . . . . 43
Appendix A.1. Addressing Examples . . . . . . . . . . . . . . . 44
Appendix A.1.1. A Message from One Person to Another with
Simple Addressing . . . . . . . . . . . . . . . . 44
Appendix A.1.2. Different Types of Mailboxes . . . . . . . . . . . 45
Appendix A.1.3. Group Addresses . . . . . . . . . . . . . . . . . 45
Appendix A.2. Reply Messages . . . . . . . . . . . . . . . . . . 46
Appendix A.3. Resent Messages . . . . . . . . . . . . . . . . . 47
Appendix A.4. Messages with Trace Fields . . . . . . . . . . . . 48
Appendix A.5. White Space, Comments, and Other Oddities . . . . 49
Appendix A.6. Obsoleted Forms . . . . . . . . . . . . . . . . . 50
Appendix A.6.1. Obsolete Addressing . . . . . . . . . . . . . . . 50
Appendix A.6.2. Obsolete Dates . . . . . . . . . . . . . . . . . . 50
Appendix A.6.3. Obsolete White Space and Comments . . . . . . . . 51
Appendix B. Differences from Earlier Specifications . . . . . 52
Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . 53
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 55
7.1. Normative References . . . . . . . . . . . . . . . . . . . 55
7.2. Informative References . . . . . . . . . . . . . . . . . . 55
4.5.6. Obsolete Resent Fields . . . . . . . . . . . . . . . . 38
4.5.7. Obsolete Trace Fields . . . . . . . . . . . . . . . . 38
4.5.8. Obsolete optional fields . . . . . . . . . . . . . . . 38
5. Security Considerations . . . . . . . . . . . . . . . . . . . 38
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
Appendix A. Example Messages . . . . . . . . . . . . . . . . . 43
Appendix A.1. Addressing Examples . . . . . . . . . . . . . . . 44
Appendix A.1.1. A Message from One Person to Another with
Simple Addressing . . . . . . . . . . . . . . . . 44
Appendix A.1.2. Different Types of Mailboxes . . . . . . . . . . . 45
Appendix A.1.3. Group Addresses . . . . . . . . . . . . . . . . . 45
Appendix A.2. Reply Messages . . . . . . . . . . . . . . . . . . 46
Appendix A.3. Resent Messages . . . . . . . . . . . . . . . . . 47
Appendix A.4. Messages with Trace Fields . . . . . . . . . . . . 48
Appendix A.5. White Space, Comments, and Other Oddities . . . . 49
Appendix A.6. Obsoleted Forms . . . . . . . . . . . . . . . . . 50
Appendix A.6.1. Obsolete Addressing . . . . . . . . . . . . . . . 50
Appendix A.6.2. Obsolete Dates . . . . . . . . . . . . . . . . . . 50
Appendix A.6.3. Obsolete White Space and Comments . . . . . . . . 51
Appendix B. Differences from Earlier Specifications . . . . . 52
Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . 53
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 55
7.1. Normative References . . . . . . . . . . . . . . . . . . . 55
7.2. Informative References . . . . . . . . . . . . . . . . . . 55
This document specifies the Internet Message Format (IMF), a syntax for text messages that are sent between computer users, within the framework of "electronic mail" messages. This specification is an update to [RFC2822], which itself superseded [RFC0822], updating it to reflect current practice and incorporating incremental changes that were specified in other RFCs such as [RFC1123].
本文件规定了互联网信息格式（IMF），即在“电子邮件”信息框架内，计算机用户之间发送的文本信息的语法。本规范是对[RFC2822]的更新，其本身取代了[RFC0822]，对其进行更新以反映当前实践，并纳入了其他RFC（如[RFC1123]）中规定的增量变更。
This document specifies a syntax only for text messages. In particular, it makes no provision for the transmission of images, audio, or other sorts of structured data in electronic mail messages. There are several extensions published, such as the MIME document series ([RFC2045], [RFC2046], [RFC2049]), which describe mechanisms for the transmission of such data through electronic mail, either by extending the syntax provided here or by structuring such messages to conform to this syntax. Those mechanisms are outside of the scope of this specification.
本文档仅为文本消息指定语法。特别是，它没有规定在电子邮件中传输图像、音频或其他类型的结构化数据。有几个已发布的扩展，如MIME文档系列（[RFC2045]、[RFC2046]、[RFC2049]），它们描述了通过电子邮件传输此类数据的机制，或者通过扩展此处提供的语法，或者通过构造此类消息以符合此语法。这些机制不在本规范的范围内。
In the context of electronic mail, messages are viewed as having an envelope and contents. The envelope contains whatever information is needed to accomplish transmission and delivery. (See [RFC5321] for a discussion of the envelope.) The contents comprise the object to be delivered to the recipient. This specification applies only to the format and some of the semantics of message contents. It contains no specification of the information in the envelope.
在电子邮件的上下文中，消息被视为具有信封和内容。信封包含完成传输和交付所需的任何信息。（有关信封的讨论，请参见[RFC5321]）内容包括要交付给收件人的对象。本规范仅适用于消息内容的格式和某些语义。它不包含信封中信息的说明。
However, some message systems may use information from the contents to create the envelope. It is intended that this specification facilitate the acquisition of such information by programs.
但是，一些消息系统可能使用内容中的信息来创建信封。本规范旨在促进程序获取此类信息。
This specification is intended as a definition of what message content format is to be passed between systems. Though some message systems locally store messages in this format (which eliminates the need for translation between formats) and others use formats that differ from the one specified in this specification, local storage is outside of the scope of this specification.
本规范旨在定义系统之间要传递的消息内容格式。尽管一些消息系统在本地以这种格式存储消息（这消除了格式之间转换的需要），而其他消息系统使用的格式与本规范中指定的格式不同，但本地存储不在本规范的范围之内。
Note: This specification is not intended to dictate the internal formats used by sites, the specific message system features that they are expected to support, or any of the characteristics of user interface programs that create or read messages. In addition, this document does not specify an encoding of the characters for either transport or storage; that is, it does not specify the number of bits used or how those bits are specifically transferred over the wire or stored on disk.
注：本规范无意规定站点使用的内部格式、它们预期支持的特定消息系统功能或创建或读取消息的用户界面程序的任何特征。此外，本文件未规定用于传输或存储的字符编码；也就是说，它没有指定所使用的位数，也没有指定这些位数是如何通过导线传输或存储在磁盘上的。
This document occasionally uses terms that appear in capital letters. When the terms "MUST", "SHOULD", "RECOMMENDED", "MUST NOT", "SHOULD NOT", and "MAY" appear capitalized, they are being used to indicate particular requirements of this specification. A discussion of the meanings of these terms appears in [RFC2119].
本文档偶尔使用大写字母表示的术语。当术语“必须”、“应该”、“建议”、“不得”、“不应该”和“可能”出现大写时，它们用于表示本规范的特殊要求。[RFC2119]中对这些术语的含义进行了讨论。
This specification uses the Augmented Backus-Naur Form (ABNF) [RFC5234] notation for the formal definitions of the syntax of messages. Characters will be specified either by a decimal value (e.g., the value %d65 for uppercase A and %d97 for lowercase A) or by a case-insensitive literal value enclosed in quotation marks (e.g., "A" for either uppercase or lowercase A).
本规范使用增广巴科斯-诺尔形式（ABNF）[RFC5234]符号对消息语法进行正式定义。字符将由十进制值（例如，大写a的值为%d65，小写a的值为%d97）或引号中包含的不区分大小写的文字值（例如，大写或小写a的值为“a”）指定。
This document is divided into several sections.
本文件分为几个部分。
This section, section 1, is a short introduction to the document.
本节，即第1节，是对本文件的简短介绍。
Section 2 lays out the general description of a message and its constituent parts. This is an overview to help the reader understand some of the general principles used in the later portions of this document. Any examples in this section MUST NOT be taken as specification of the formal syntax of any part of a message.
第2节列出了消息及其组成部分的一般描述。这是一个概述，帮助读者理解本文档后面部分中使用的一些一般原则。不得将本节中的任何示例视为消息任何部分的形式语法规范。
Section 3 specifies formal ABNF rules for the structure of each part of a message (the syntax) and describes the relationship between those parts and their meaning in the context of a message (the semantics). That is, it lays out the actual rules for the structure of each part of a message (the syntax) as well as a description of the parts and instructions for their interpretation (the semantics). This includes analysis of the syntax and semantics of subparts of messages that have specific structure. The syntax included in section 3 represents messages as they MUST be created. There are also notes in section 3 to indicate if any of the options specified in the syntax SHOULD be used over any of the others.
第3节为消息的每个部分的结构（语法）指定了形式ABNF规则，并描述了这些部分之间的关系及其在消息上下文中的意义（语义）。也就是说，它列出了消息每个部分的结构（语法）的实际规则，以及部分的描述和解释说明（语义）。这包括分析具有特定结构的消息子部分的语法和语义。第3节中包含的语法表示必须创建的消息。第3节中也有注释，说明语法中指定的任何选项是否应优于其他选项。
Both sections 2 and 3 describe messages that are legal to generate for purposes of this specification.
第2节和第3节都描述了为本规范的目的而合法生成的消息。
Section 4 of this document specifies an "obsolete" syntax. There are references in section 3 to these obsolete syntactic elements. The rules of the obsolete syntax are elements that have appeared in earlier versions of this specification or have previously been widely used in Internet messages. As such, these elements MUST be interpreted by parsers of messages in order to be conformant to this specification. However, since items in this syntax have been determined to be non-interoperable or to cause significant problems for recipients of messages, they MUST NOT be generated by creators of conformant messages.
本文件第4节规定了“过时”语法。第3节中提到了这些过时的语法元素。过时语法的规则是在本规范的早期版本中出现的元素，或者以前在Internet消息中广泛使用的元素。因此，这些元素必须由消息解析器解释，以符合本规范。但是，由于此语法中的项已被确定为不可互操作或对邮件收件人造成重大问题，因此它们不能由一致邮件的创建者生成。
Section 5 details security considerations to take into account when implementing this specification.
第5节详细说明了在实施本规范时应考虑的安全注意事项。
Appendix A lists examples of different sorts of messages. These examples are not exhaustive of the types of messages that appear on the Internet, but give a broad overview of certain syntactic forms.
附录A列出了各种消息的示例。这些例子并不是互联网上出现的所有消息类型，而是对某些语法形式的概括。
Appendix B lists the differences between this specification and earlier specifications for Internet messages.
附录B列出了本规范与早期互联网信息规范之间的差异。
Appendix C contains acknowledgements.
附录C包含确认。
At the most basic level, a message is a series of characters. A message that is conformant with this specification is composed of characters with values in the range of 1 through 127 and interpreted as US-ASCII [ANSI.X3-4.1986] characters. For brevity, this document sometimes refers to this range of characters as simply "US-ASCII characters".
在最基本的层面上，消息是一系列字符。符合本规范的消息由值在1到127之间的字符组成，并解释为US-ASCII[ANSI.X3-4.1986]字符。为简洁起见，本文档有时将此范围的字符简称为“US-ASCII字符”。
Note: This document specifies that messages are made up of characters in the US-ASCII range of 1 through 127. There are other documents, specifically the MIME document series ([RFC2045], [RFC2046], [RFC2047], [RFC2049], [RFC4288], [RFC4289]), that extend this specification to allow for values outside of that range. Discussion of those mechanisms is not within the scope of this specification.
注意：本文档规定消息由US-ASCII范围1到127的字符组成。还有其他文档，特别是MIME文档系列（[RFC2045]、[RFC2046]、[RFC2047]、[RFC2049]、[RFC4288]、[RFC4289]），它们扩展了此规范，以允许超出该范围的值。对这些机制的讨论不在本规范的范围内。
Messages are divided into lines of characters. A line is a series of characters that is delimited with the two characters carriage-return and line-feed; that is, the carriage return (CR) character (ASCII value 13) followed immediately by the line feed (LF) character (ASCII value 10). (The carriage return/line feed pair is usually written in this document as "CRLF".)
消息被分成几行字符。行是一系列字符，由回车符和换行符两个字符分隔；也就是说，回车（CR）字符（ASCII值13）后跟换行（LF）字符（ASCII值10）。（本文件中，回车/换行符对通常写为“CRLF”。）
A message consists of header fields (collectively called "the header section of the message") followed, optionally, by a body. The header section is a sequence of lines of characters with special syntax as defined in this specification. The body is simply a sequence of characters that follows the header section and is separated from the header section by an empty line (i.e., a line with nothing preceding the CRLF).
消息由标题字段（统称为“消息的标题部分”）组成，后面可选地跟一个正文。标题部分是具有本规范中定义的特殊语法的字符行序列。正文只是标题部分后面的一个字符序列，与标题部分之间用空行分隔（即，CRLF前面没有任何内容的行）。
Note: Common parlance and earlier versions of this specification use the term "header" to either refer to the entire header section or to refer to an individual header field. To avoid ambiguity, this document does not use the terms "header" or "headers" in isolation, but instead always uses "header field" to refer to the individual field and "header section" to refer to the entire collection.
注：本规范的通用术语和早期版本使用术语“标题”来表示整个标题部分或单个标题字段。为避免歧义，本文档不单独使用术语“标题”或“标题”，而是始终使用“标题字段”来表示单个字段，“标题部分”来表示整个集合。
There are two limits that this specification places on the number of characters in a line. Each line of characters MUST be no more than 998 characters, and SHOULD be no more than 78 characters, excluding the CRLF.
本规范对一行中的字符数有两个限制。除CRLF外，每行字符不得超过998个字符，且不得超过78个字符。
The 998 character limit is due to limitations in many implementations that send, receive, or store IMF messages which simply cannot handle more than 998 characters on a line. Receiving implementations would do well to handle an arbitrarily large number of characters in a line for robustness sake. However, there are so many implementations that (in compliance with the transport requirements of [RFC5321]) do not accept messages containing more than 1000 characters including the CR and LF per line, it is important for implementations not to create such messages.
998个字符的限制是由于许多发送、接收或存储IMF消息的实现中的限制，这些消息一行不能处理超过998个字符。为了健壮性，接收实现最好处理一行中任意大量的字符。然而，有太多的实现（符合[RFC5321]的传输要求）不接受包含超过1000个字符（包括每行的CR和LF）的消息，因此实现不创建此类消息非常重要。
The more conservative 78 character recommendation is to accommodate the many implementations of user interfaces that display these messages which may truncate, or disastrously wrap, the display of more than 78 characters per line, in spite of the fact that such implementations are non-conformant to the intent of this specification (and that of [RFC5321] if they actually cause information to be lost). Again, even though this limitation is put on messages, it is incumbent upon implementations that display messages to handle an arbitrarily large number of characters in a line (certainly at least up to the 998 character limit) for the sake of robustness.
更保守的78个字符的建议是适应显示这些消息的用户界面的许多实现，这些消息可能会截断或灾难性地包装每行超过78个字符的显示，尽管这些实现不符合本规范的意图（以及[RFC5321]如果它们确实导致信息丢失）。同样，即使对消息施加了此限制，显示消息的实现也有义务处理一行中任意大量的字符（当然至少达到998个字符的限制），以确保健壮性。
Header fields are lines beginning with a field name, followed by a colon (":"), followed by a field body, and terminated by CRLF. A field name MUST be composed of printable US-ASCII characters (i.e., characters that have values between 33 and 126, inclusive), except colon. A field body may be composed of printable US-ASCII characters as well as the space (SP, ASCII value 32) and horizontal tab (HTAB, ASCII value 9) characters (together known as the white space characters, WSP). A field body MUST NOT include CR and LF except when used in "folding" and "unfolding", as described in section 2.2.3. All field bodies MUST conform to the syntax described in sections 3 and 4 of this specification.
标题字段是以字段名开头的行，后跟冒号（“：”），后跟字段正文，并以CRLF结尾。字段名必须由可打印的US-ASCII字符（即值介于33和126之间的字符，包括在内）组成，冒号除外。字段正文可以由可打印的US-ASCII字符以及空格（SP，ASCII值32）和水平制表符（HTAB，ASCII值9）字符（统称为空白字符，WSP）组成。现场主体不得包括CR和LF，除非用于第2.2.3节所述的“折叠”和“展开”。所有字段体必须符合本规范第3节和第4节中描述的语法。
Some field bodies in this specification are defined simply as "unstructured" (which is specified in section 3.2.5 as any printable US-ASCII characters plus white space characters) with no further restrictions. These are referred to as unstructured field bodies. Semantically, unstructured field bodies are simply to be treated as a single line of characters with no further processing (except for "folding" and "unfolding" as described in section 2.2.3).
本规范中的一些字段体仅定义为“非结构化”（第3.2.5节规定为任何可打印的US-ASCII字符加空白字符），没有进一步的限制。这些被称为非结构化场体。从语义上讲，非结构化字段体仅被视为一行字符，无需进一步处理（第2.2.3节所述的“折叠”和“展开”除外）。
Some field bodies in this specification have a syntax that is more restrictive than the unstructured field bodies described above. These are referred to as "structured" field bodies. Structured field bodies are sequences of specific lexical tokens as described in sections 3 and 4 of this specification. Many of these tokens are allowed (according to their syntax) to be introduced or end with comments (as described in section 3.2.2) as well as the white space characters, and those white space characters are subject to "folding" and "unfolding" as described in section 2.2.3. Semantic analysis of structured field bodies is given along with their syntax.
本规范中的某些字段体的语法比上述非结构化字段体更具限制性。这些被称为“结构化”场体。结构化字段体是特定词汇标记的序列，如本规范第3节和第4节所述。允许（根据其语法）引入这些标记中的许多标记，或以注释（如第3.2.2节所述）以及空白字符结尾，并且这些空白字符会按照第2.2.3节所述进行“折叠”和“展开”。对结构化字段体及其语法进行了语义分析。
Each header field is logically a single line of characters comprising the field name, the colon, and the field body. For convenience however, and to deal with the 998/78 character limitations per line, the field body portion of a header field can be split into a multiple-line representation; this is called "folding". The general rule is that wherever this specification allows for folding white space (not simply WSP characters), a CRLF may be inserted before any WSP.
每个标题字段在逻辑上是一行字符，包括字段名、冒号和字段正文。然而，为了方便起见，为了处理每行998/78个字符的限制，可以将标题字段的字段体部分拆分为多行表示；这就是所谓的“折叠”。一般规则是，只要本规范允许折叠空白（不仅仅是WSP字符），就可以在任何WSP之前插入CRLF。
For example, the header field:
例如，标题字段：
Subject: This is a test
主题：这是一个测试
can be represented as:
可表示为：
Subject: This is a test
主题：这是一个测试
Note: Though structured field bodies are defined in such a way that folding can take place between many of the lexical tokens (and even within some of the lexical tokens), folding SHOULD be limited to placing the CRLF at higher-level syntactic breaks. For instance, if a field body is defined as comma-separated values, it is recommended that folding occur after the comma separating the structured items in preference to other places where the field could be folded, even if it is allowed elsewhere.
注意：虽然结构化字段体的定义方式是，折叠可以在许多词汇标记之间发生（甚至在一些词汇标记内），但折叠应限于将CRLF置于更高层次的语法中断处。例如，如果字段正文定义为逗号分隔的值，则建议在逗号分隔结构化项之后进行折叠，而不是在可以折叠字段的其他位置进行折叠，即使在其他位置也允许。
The process of moving from this folded multiple-line representation of a header field to its single line representation is called "unfolding". Unfolding is accomplished by simply removing any CRLF that is immediately followed by WSP. Each header field should be treated in its unfolded form for further syntactic and semantic evaluation. An unfolded header field has no length restriction and therefore may be indeterminately long.
从标题字段的折叠多行表示移动到其单行表示的过程称为“展开”。展开是通过简单地删除任何CRLF，然后立即执行WSP来完成的。每个标题字段应以其展开形式进行处理，以便进一步进行语法和语义评估。展开的标题字段没有长度限制，因此可能是不确定的长度。
The body of a message is simply lines of US-ASCII characters. The only two limitations on the body are as follows:
消息的主体只是US-ASCII字符行。车身上仅有的两个限制如下：
o CR and LF MUST only occur together as CRLF; they MUST NOT appear independently in the body. o Lines of characters in the body MUST be limited to 998 characters, and SHOULD be limited to 78 characters, excluding the CRLF.
o CR和LF只能作为CRLF一起出现；它们不能单独出现在体内。o正文中的字符行必须限制为998个字符，并且应限制为78个字符，CRLF除外。
Note: As was stated earlier, there are other documents, specifically the MIME documents ([RFC2045], [RFC2046], [RFC2049], [RFC4288], [RFC4289]), that extend (and limit) this specification to allow for different sorts of message bodies. Again, these mechanisms are beyond the scope of this document.
注意：如前所述，还有其他文档，特别是MIME文档（[RFC2045]、[RFC2046]、[RFC2049]、[RFC4288]、[RFC4289]），它们扩展（和限制）了本规范，以允许不同种类的消息体。同样，这些机制超出了本文件的范围。
The syntax as given in this section defines the legal syntax of Internet messages. Messages that are conformant to this specification MUST conform to the syntax in this section. If there are options in this section where one option SHOULD be generated, that is indicated either in the prose or in a comment next to the syntax.
本节给出的语法定义了Internet消息的合法语法。符合本规范的消息必须符合本节中的语法。如果本节中有选项，其中应生成一个选项，则在散文或语法旁边的注释中指出。
For the defined expressions, a short description of the syntax and use is given, followed by the syntax in ABNF, followed by a semantic analysis. The following primitive tokens that are used but otherwise unspecified are taken from the "Core Rules" of [RFC5234], Appendix B.1: CR, LF, CRLF, HTAB, SP, WSP, DQUOTE, DIGIT, ALPHA, and VCHAR.
对于定义的表达式，将给出语法和用法的简短描述，然后是ABNF中的语法，然后是语义分析。以下使用但未指定的原始标记取自[RFC5234]附录B.1中的“核心规则”：CR、LF、CRLF、HTAB、SP、WSP、DQUOTE、DIGIT、ALPHA和VCHAR。
In some of the definitions, there will be non-terminals whose names start with "obs-". These "obs-" elements refer to tokens defined in the obsolete syntax in section 4. In all cases, these productions are to be ignored for the purposes of generating legal Internet messages and MUST NOT be used as part of such a message. However, when interpreting messages, these tokens MUST be honored as part of the legal syntax. In this sense, section 3 defines a grammar for the generation of messages, with "obs-" elements that are to be ignored, while section 4 adds grammar for the interpretation of messages.
In some of the definitions, there will be non-terminals whose names start with "obs-". These "obs-" elements refer to tokens defined in the obsolete syntax in section 4. In all cases, these productions are to be ignored for the purposes of generating legal Internet messages and MUST NOT be used as part of such a message. However, when interpreting messages, these tokens MUST be honored as part of the legal syntax. In this sense, section 3 defines a grammar for the generation of messages, with "obs-" elements that are to be ignored, while section 4 adds grammar for the interpretation of messages.translate error, please retry
The following rules are used to define an underlying lexical analyzer, which feeds tokens to the higher-level parsers. This section defines the tokens used in structured header field bodies.
以下规则用于定义底层词法分析器，该分析器将令牌提供给更高级别的解析器。本节定义结构化标题字段正文中使用的标记。
Note: Readers of this specification need to pay special attention to how these lexical tokens are used in both the lower-level and higher-level syntax later in the document. Particularly, the white space tokens and the comment tokens defined in section 3.2.2 get used in the lower-level tokens defined here, and those lower-level tokens are in turn used as parts of the higher-level tokens defined later. Therefore, white space and comments may be allowed in the higher-level tokens even though they may not explicitly appear in a particular definition.
注意：本规范的读者需要特别注意这些词汇标记在文档后面的较低级别和较高级别语法中是如何使用的。特别是，第3.2.2节中定义的空白标记和注释标记将在此处定义的较低级别标记中使用，而这些较低级别标记将依次用作稍后定义的较高级别标记的一部分。因此，在更高级别的标记中可以使用空格和注释，即使它们可能没有明确出现在特定定义中。
Some characters are reserved for special interpretation, such as delimiting lexical tokens. To permit use of these characters as uninterpreted data, a quoting mechanism is provided.
有些字符保留用于特殊解释，例如分隔词汇标记。为了允许将这些字符用作未解释的数据，提供了引用机制。
quoted-pair = ("\" (VCHAR / WSP)) / obs-qp
quoted-pair = ("\" (VCHAR / WSP)) / obs-qp
Where any quoted-pair appears, it is to be interpreted as the character alone. That is to say, the "\" character that appears as part of a quoted-pair is semantically "invisible".
如果出现任何带引号的对，则仅将其解释为字符。也就是说，作为引用对的一部分出现的“\”字符在语义上是“不可见的”。
Note: The "\" character may appear in a message where it is not part of a quoted-pair. A "\" character that does not appear in a quoted-pair is not semantically invisible. The only places in this specification where quoted-pair currently appears are ccontent, qcontent, and in obs-dtext in section 4.
注意：“\”字符可能出现在不属于引号对的消息中。引号对中未出现的“\”字符在语义上不可见。在本规范中，引用对当前出现的唯一位置是第4节中的ccontent、qcontent和obs dtext。
White space characters, including white space used in folding (described in section 2.2.3), may appear between many elements in header field bodies. Also, strings of characters that are treated as comments may be included in structured field bodies as characters enclosed in parentheses. The following defines the folding white space (FWS) and comment constructs.
空白字符，包括折叠时使用的空白字符（如第2.2.3节所述），可能出现在标题字段正文中的许多元素之间。此外，被视为注释的字符串可以作为括号中的字符包含在结构化字段体中。下面定义了折叠空白（FWS）和注释结构。
Strings of characters enclosed in parentheses are considered comments so long as they do not appear within a "quoted-string", as defined in section 3.2.4. Comments may nest.
根据第3.2.4节的定义，括号内的字符串只要不出现在“带引号的字符串”中，就被视为注释。评论可以嵌套。
There are several places in this specification where comments and FWS may be freely inserted. To accommodate that syntax, an additional token for "CFWS" is defined for places where comments and/or FWS can occur. However, where CFWS occurs in this specification, it MUST NOT be inserted in such a way that any line of a folded header field is made up entirely of WSP characters and nothing else.
本规范中有几个地方可以自由插入注释和FW。为了适应这种语法，为“CFWS”定义了一个额外的标记，用于可能出现注释和/或FWS的地方。但是，在本规范中出现CFW的地方，插入CFW的方式不得使折叠头字段的任何一行完全由WSP字符而不是其他字符组成。
FWS = ([*WSP CRLF] 1*WSP) / obs-FWS
; Folding white space
FWS = ([*WSP CRLF] 1*WSP) / obs-FWS
; Folding white space
ctext = %d33-39 / ; Printable US-ASCII
%d42-91 / ; characters not including
%d93-126 / ; "(", ")", or "\"
obs-ctext
ctext = %d33-39 / ; Printable US-ASCII
%d42-91 / ; characters not including
%d93-126 / ; "(", ")", or "\"
obs-ctext
ccontent = ctext / quoted-pair / comment
ccontent = ctext / quoted-pair / comment
comment = "(" *([FWS] ccontent) [FWS] ")"
comment = "(" *([FWS] ccontent) [FWS] ")"
CFWS = (1*([FWS] comment) [FWS]) / FWS
CFWS = (1*([FWS] comment) [FWS]) / FWS
Throughout this specification, where FWS (the folding white space token) appears, it indicates a place where folding, as discussed in section 2.2.3, may take place. Wherever folding appears in a message (that is, a header field body containing a CRLF followed by any WSP), unfolding (removal of the CRLF) is performed before any further semantic analysis is performed on that header field according to this specification. That is to say, any CRLF that appears in FWS is semantically "invisible".
在本规范中，当FWS（折叠空白标记）出现时，表示第2.2.3节中讨论的折叠可能发生的位置。在消息中出现折叠的地方（即，包含CRLF的标题字段正文后跟任何WSP），在根据本规范对该标题字段执行任何进一步语义分析之前，将执行展开（CRLF的移除）。也就是说，出现在FWS中的任何CRLF在语义上都是“不可见的”。
A comment is normally used in a structured field body to provide some human-readable informational text. Since a comment is allowed to contain FWS, folding is permitted within the comment. Also note that since quoted-pair is allowed in a comment, the parentheses and backslash characters may appear in a comment, so long as they appear as a quoted-pair. Semantically, the enclosing parentheses are not part of the comment; the comment is what is contained between the two parentheses. As stated earlier, the "\" in any quoted-pair and the CRLF in any FWS that appears within the comment are semantically "invisible" and therefore not part of the comment either.
注释通常用于结构化字段正文中，以提供一些人类可读的信息文本。由于允许注释包含FWS，因此允许在注释内折叠。还请注意，由于注释中允许使用引号对，因此括号和反斜杠字符可能会出现在注释中，只要它们显示为引号对。从语义上讲，括号不是注释的一部分；注释包含在两个括号之间。如前所述，注释中出现的任何引用对中的“\”和任何FWS中的CRLF在语义上是“不可见的”，因此也不是注释的一部分。
Runs of FWS, comment, or CFWS that occur between lexical tokens in a structured header field are semantically interpreted as a single space character.
在结构化头字段的词法标记之间出现的FW、comment或CFW的运行在语义上被解释为单个空格字符。
Several productions in structured header field bodies are simply strings of certain basic characters. Such productions are called atoms.
结构化标题字段体中的几个结果只是某些基本字符的字符串。这种产物称为原子。
Some of the structured header field bodies also allow the period character (".", ASCII value 46) within runs of atext. An additional "dot-atom" token is defined for those purposes.
一些结构化标题字段正文还允许在atext的运行中使用句点字符（“.”，ASCII值46）。为此，定义了一个附加的“点原子”标记。
Note: The "specials" token does not appear anywhere else in this specification. It is simply the visible (i.e., non-control, non-white space) characters that do not appear in atext. It is provided only because it is useful for implementers who use tools that lexically analyze messages. Each of the characters in specials can be used to indicate a tokenization point in lexical analysis.
注意：“特殊”标记不会出现在本规范的任何其他地方。只是atext中不显示的可见字符（即非控制字符、非空白字符）。之所以提供它，是因为它对使用词汇分析消息的工具的实现者有用。specials中的每个字符都可以用来表示词汇分析中的标记化点。
atext = ALPHA / DIGIT / ; Printable US-ASCII
"!" / "#" / ; characters not including
"$" / "%" / ; specials. Used for atoms.
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
atext = ALPHA / DIGIT / ; Printable US-ASCII
"!" / "#" / ; characters not including
"$" / "%" / ; specials. Used for atoms.
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
atom = [CFWS] 1*atext [CFWS]
atom = [CFWS] 1*atext [CFWS]
dot-atom-text = 1*atext *("." 1*atext)
dot-atom-text = 1*atext *("." 1*atext)
dot-atom = [CFWS] dot-atom-text [CFWS]
dot-atom = [CFWS] dot-atom-text [CFWS]
specials = "(" / ")" / ; Special characters that do
"<" / ">" / ; not appear in atext
"[" / "]" /
":" / ";" /
"@" / "\" /
"," / "." /
DQUOTE
specials = "(" / ")" / ; Special characters that do
"<" / ">" / ; not appear in atext
"[" / "]" /
":" / ";" /
"@" / "\" /
"," / "." /
DQUOTE
Both atom and dot-atom are interpreted as a single unit, comprising the string of characters that make it up. Semantically, the optional comments and FWS surrounding the rest of the characters are not part of the atom; the atom is only the run of atext characters in an atom, or the atext and "." characters in a dot-atom.
原子和点原子都被解释为单个单元，由组成它的字符串组成。语义上，围绕其余字符的可选注释和FW不是atom的一部分；atom只是atom中atext字符的运行，或者是点atom中atext和“.”字符的运行。
Strings of characters that include characters other than those allowed in atoms can be represented in a quoted string format, where the characters are surrounded by quote (DQUOTE, ASCII value 34) characters.
包含原子中不允许的字符的字符串可以用引号字符串格式表示，其中字符由引号（DQUOTE，ASCII值34）字符包围。
qtext = %d33 / ; Printable US-ASCII
%d35-91 / ; characters not including
%d93-126 / ; "\" or the quote character
obs-qtext
qtext = %d33 / ; Printable US-ASCII
%d35-91 / ; characters not including
%d93-126 / ; "\" or the quote character
obs-qtext
qcontent = qtext / quoted-pair
qcontent = qtext / quoted-pair
quoted-string = [CFWS]
DQUOTE *([FWS] qcontent) [FWS] DQUOTE
[CFWS]
quoted-string = [CFWS]
DQUOTE *([FWS] qcontent) [FWS] DQUOTE
[CFWS]
A quoted-string is treated as a unit. That is, quoted-string is identical to atom, semantically. Since a quoted-string is allowed to contain FWS, folding is permitted. Also note that since quoted-pair is allowed in a quoted-string, the quote and backslash characters may appear in a quoted-string so long as they appear as a quoted-pair.
带引号的字符串被视为一个单元。也就是说，带引号的字符串在语义上与atom相同。由于带引号的字符串允许包含FWS，因此允许折叠。还要注意的是，由于在带引号的字符串中允许使用引号的对，因此引号和反斜杠字符可能会出现在带引号的字符串中，只要它们显示为带引号的对。
Semantically, neither the optional CFWS outside of the quote characters nor the quote characters themselves are part of the quoted-string; the quoted-string is what is contained between the two quote characters. As stated earlier, the "\" in any quoted-pair and the CRLF in any FWS/CFWS that appears within the quoted-string are semantically "invisible" and therefore not part of the quoted-string either.
语义上，引号字符之外的可选CFW和引号字符本身都不是引号字符串的一部分；带引号的字符串包含在两个引号字符之间。如前所述，任何引用对中的“\”和出现在引用字符串中的任何FWS/CFWS中的CRLF在语义上是“不可见的”，因此也不是引用字符串的一部分。
Three additional tokens are defined: word and phrase for combinations of atoms and/or quoted-strings, and unstructured for use in unstructured header fields and in some places within structured header fields.
另外定义了三个标记：用于原子和/或带引号字符串组合的单词和短语，以及用于非结构化标题字段和结构化标题字段中某些位置的非结构化标记。
word = atom / quoted-string
word = atom / quoted-string
phrase = 1*word / obs-phrase
phrase = 1*word / obs-phrase
unstructured = (*([FWS] VCHAR) *WSP) / obs-unstruct
unstructured = (*([FWS] VCHAR) *WSP) / obs-unstruct
Date and time values occur in several header fields. This section specifies the syntax for a full date and time specification. Though folding white space is permitted throughout the date-time specification, it is RECOMMENDED that a single space be used in each place that FWS appears (whether it is required or optional); some older implementations will not interpret longer sequences of folding white space correctly.
日期和时间值出现在多个标题字段中。本节指定完整日期和时间规范的语法。尽管在整个日期-时间规范中允许折叠空格，但建议在FWS出现的每个位置使用单个空格（无论是必需的还是可选的）；一些较旧的实现无法正确解释较长的折叠空白序列。
date-time = [ day-of-week "," ] date time [CFWS]
date-time = [ day-of-week "," ] date time [CFWS]
day-of-week = ([FWS] day-name) / obs-day-of-week
day-of-week = ([FWS] day-name) / obs-day-of-week
day-name = "Mon" / "Tue" / "Wed" / "Thu" /
"Fri" / "Sat" / "Sun"
day-name = "Mon" / "Tue" / "Wed" / "Thu" /
"Fri" / "Sat" / "Sun"
date = day month year
date = day month year
day = ([FWS] 1*2DIGIT FWS) / obs-day
day = ([FWS] 1*2DIGIT FWS) / obs-day
month = "Jan" / "Feb" / "Mar" / "Apr" /
"May" / "Jun" / "Jul" / "Aug" /
"Sep" / "Oct" / "Nov" / "Dec"
month = "Jan" / "Feb" / "Mar" / "Apr" /
"May" / "Jun" / "Jul" / "Aug" /
"Sep" / "Oct" / "Nov" / "Dec"
year = (FWS 4*DIGIT FWS) / obs-year
year = (FWS 4*DIGIT FWS) / obs-year
time = time-of-day zone
time = time-of-day zone
time-of-day = hour ":" minute [ ":" second ]
time-of-day = hour ":" minute [ ":" second ]
hour = 2DIGIT / obs-hour
hour = 2DIGIT / obs-hour
minute = 2DIGIT / obs-minute
minute = 2DIGIT / obs-minute
second = 2DIGIT / obs-second
second = 2DIGIT / obs-second
zone = (FWS ( "+" / "-" ) 4DIGIT) / obs-zone
zone = (FWS ( "+" / "-" ) 4DIGIT) / obs-zone
The day is the numeric day of the month. The year is any numeric year 1900 or later.
日期是一个月中的数字日期。年份是1900年或更晚的任何数字年份。
The time-of-day specifies the number of hours, minutes, and optionally seconds since midnight of the date indicated.
一天中的时间指定从指定日期的午夜开始的小时数、分钟数和秒数（可选）。
The date and time-of-day SHOULD express local time.
一天中的日期和时间应表示为当地时间。
The zone specifies the offset from Coordinated Universal Time (UTC, formerly referred to as "Greenwich Mean Time") that the date and time-of-day represent. The "+" or "-" indicates whether the time-of-day is ahead of (i.e., east of) or behind (i.e., west of) Universal Time. The first two digits indicate the number of hours difference from Universal Time, and the last two digits indicate the number of additional minutes difference from Universal Time. (Hence, +hhmm means +(hh * 60 + mm) minutes, and -hhmm means -(hh * 60 + mm) minutes). The form "+0000" SHOULD be used to indicate a time zone at Universal Time. Though "-0000" also indicates Universal Time, it is
分区指定日期和时间所代表的与协调世界时（UTC，以前称为“格林威治标准时间”）的偏移量。“+”或“-”表示一天中的时间是在世界时之前（即在世界时的东部）还是在世界时之后（即在世界时的西部）。前两位数字表示与世界时相差的小时数，后两位数字表示与世界时相差的额外分钟数。（因此，+hhmm表示+（hh*60+mm）分钟，-hhmm表示-（hh*60+mm）分钟）。表格“+0000”应用于表示世界时的时区。虽然“-0000”也表示世界时，但它是
used to indicate that the time was generated on a system that may be in a local time zone other than Universal Time and that the date-time contains no information about the local time zone.
用于指示时间是在系统上生成的，该系统可能位于世界时以外的本地时区，并且日期时间不包含有关本地时区的信息。
A date-time specification MUST be semantically valid. That is, the day-of-week (if included) MUST be the day implied by the date, the numeric day-of-month MUST be between 1 and the number of days allowed for the specified month (in the specified year), the time-of-day MUST be in the range 00:00:00 through 23:59:60 (the number of seconds allowing for a leap second; see [RFC1305]), and the last two digits of the zone MUST be within the range 00 through 59.
日期时间规范必须在语义上有效。也就是说，星期几（如果包括）必须是日期所隐含的日期，数字的月份日期必须介于1和指定月份（在指定年份）允许的天数之间，时间必须在00:00:00到23:59:60之间（允许闰秒的秒数；请参见[RFC1305]），区域的最后两位数字必须在00到59之间。
Addresses occur in several message header fields to indicate senders and recipients of messages. An address may either be an individual mailbox, or a group of mailboxes.
地址出现在多个邮件标题字段中，用于指示邮件的发件人和收件人。地址可以是单个邮箱，也可以是一组邮箱。
address = mailbox / group
address = mailbox / group
mailbox = name-addr / addr-spec
mailbox = name-addr / addr-spec
name-addr = [display-name] angle-addr
name-addr = [display-name] angle-addr
angle-addr = [CFWS] "<" addr-spec ">" [CFWS] /
obs-angle-addr
angle-addr = [CFWS] "<" addr-spec ">" [CFWS] /
obs-angle-addr
group = display-name ":" [group-list] ";" [CFWS]
group = display-name ":" [group-list] ";" [CFWS]
display-name = phrase
display-name = phrase
mailbox-list = (mailbox *("," mailbox)) / obs-mbox-list
mailbox-list = (mailbox *("," mailbox)) / obs-mbox-list
address-list = (address *("," address)) / obs-addr-list
address-list = (address *("," address)) / obs-addr-list
group-list = mailbox-list / CFWS / obs-group-list
group-list = mailbox-list / CFWS / obs-group-list
A mailbox receives mail. It is a conceptual entity that does not necessarily pertain to file storage. For example, some sites may choose to print mail on a printer and deliver the output to the addressee's desk.
邮箱接收邮件。它是一个概念实体，不一定属于文件存储。例如，一些网站可能选择在打印机上打印邮件，并将输出发送到收件人的办公桌。
Normally, a mailbox is composed of two parts: (1) an optional display name that indicates the name of the recipient (which can be a person or a system) that could be displayed to the user of a mail application, and (2) an addr-spec address enclosed in angle brackets
通常，邮箱由两部分组成：（1）一个可选的显示名称，表示可以向邮件应用程序的用户显示的收件人（可以是个人或系统）的名称；（2）尖括号中包含的地址规范地址
("<" and ">"). There is an alternate simple form of a mailbox where the addr-spec address appears alone, without the recipient's name or the angle brackets. The Internet addr-spec address is described in section 3.4.1.
（“<”和“>”）。还有一种简单的邮箱形式，其中addr spec地址单独显示，没有收件人的姓名或尖括号。第3.4.1节描述了互联网地址规范地址。
Note: Some legacy implementations used the simple form where the addr-spec appears without the angle brackets, but included the name of the recipient in parentheses as a comment following the addr-spec. Since the meaning of the information in a comment is unspecified, implementations SHOULD use the full name-addr form of the mailbox, instead of the legacy form, to specify the display name associated with a mailbox. Also, because some legacy implementations interpret the comment, comments generally SHOULD NOT be used in address fields to avoid confusing such implementations.
注意：一些旧式实现使用简单的形式，其中addr spec不带尖括号，但在addr-spec后面的括号中包含收件人姓名作为注释。由于注释中信息的含义未指定，因此实现应使用邮箱的全名addr形式，指定与邮箱关联的显示名称，而不是传统表单。此外，由于一些遗留实现解释注释，因此通常不应在地址字段中使用注释，以避免混淆此类实现。
When it is desirable to treat several mailboxes as a single unit (i.e., in a distribution list), the group construct can be used. The group construct allows the sender to indicate a named group of recipients. This is done by giving a display name for the group, followed by a colon, followed by a comma-separated list of any number of mailboxes (including zero and one), and ending with a semicolon. Because the list of mailboxes can be empty, using the group construct is also a simple way to communicate to recipients that the message was sent to one or more named sets of recipients, without actually providing the individual mailbox address for any of those recipients.
当需要将多个邮箱视为单个单元（即，在通讯组列表中）时，可以使用组结构。组构造允许发送方指示一组指定的收件人。这是通过以下方式完成的：为组指定显示名称，后跟冒号，后跟以逗号分隔的任意数量邮箱列表（包括0和1），并以分号结尾。由于邮箱列表可以为空，因此使用组构造也是一种简单的方法，可以向收件人传达邮件已发送到一个或多个命名的收件人集，而无需实际提供这些收件人的单个邮箱地址。
An addr-spec is a specific Internet identifier that contains a locally interpreted string followed by the at-sign character ("@", ASCII value 64) followed by an Internet domain. The locally interpreted string is either a quoted-string or a dot-atom. If the string can be represented as a dot-atom (that is, it contains no characters other than atext characters or "." surrounded by atext characters), then the dot-atom form SHOULD be used and the quoted-string form SHOULD NOT be used. Comments and folding white space SHOULD NOT be used around the "@" in the addr-spec.
addr规范是一个特定的Internet标识符，它包含一个本地解释的字符串，后跟at符号字符（“@”，ASCII值64），后跟一个Internet域。本地解释的字符串是带引号的字符串或点原子。如果字符串可以表示为点原子（即，它不包含除atext字符或由atext字符包围的“.”以外的字符），则应使用点原子形式，而不应使用带引号的字符串形式。addr-spec中的“@”周围不应使用注释和折叠空格。
Note: A liberal syntax for the domain portion of addr-spec is given here. However, the domain portion contains addressing information specified by and used in other protocols (e.g., [RFC1034], [RFC1035], [RFC1123], [RFC5321]). It is therefore incumbent upon implementations to conform to the syntax of addresses for the context in which they are used.
注意：这里给出了addr规范的域部分的自由语法。然而，域部分包含由其他协议（例如，[RFC1034]、[RFC1035]、[RFC1123]、[RFC5321]）指定并在其中使用的寻址信息。因此，实现必须遵守使用地址的上下文的地址语法。
addr-spec = local-part "@" domain
addr spec=本地部分“@”域
local-part = dot-atom / quoted-string / obs-local-part
local-part = dot-atom / quoted-string / obs-local-part
domain = dot-atom / domain-literal / obs-domain
domain = dot-atom / domain-literal / obs-domain
domain-literal = [CFWS] "[" *([FWS] dtext) [FWS] "]" [CFWS]
domain-literal = [CFWS] "[" *([FWS] dtext) [FWS] "]" [CFWS]
dtext = %d33-90 / ; Printable US-ASCII
%d94-126 / ; characters not including
obs-dtext ; "[", "]", or "\"
dtext = %d33-90 / ; Printable US-ASCII
%d94-126 / ; characters not including
obs-dtext ; "[", "]", or "\"
The domain portion identifies the point to which the mail is delivered. In the dot-atom form, this is interpreted as an Internet domain name (either a host name or a mail exchanger name) as described in [RFC1034], [RFC1035], and [RFC1123]. In the domain-literal form, the domain is interpreted as the literal Internet address of the particular host. In both cases, how addressing is used and how messages are transported to a particular host is covered in separate documents, such as [RFC5321]. These mechanisms are outside of the scope of this document.
域部分标识邮件传递到的点。在点原子形式中，这被解释为[RFC1034]、[RFC1035]和[RFC1123]中所述的互联网域名（主机名或邮件交换器名）。在域文本形式中，域被解释为特定主机的文本Internet地址。在这两种情况下，如何使用寻址以及如何将消息传输到特定主机都在单独的文档中介绍，例如[RFC5321]。这些机制不在本文件的范围之内。
The local-part portion is a domain-dependent string. In addresses, it is simply interpreted on the particular host as a name of a particular mailbox.
本地部分是依赖于域的字符串。在地址中，它只是在特定主机上解释为特定邮箱的名称。
A message consists of header fields, optionally followed by a message body. Lines in a message MUST be a maximum of 998 characters excluding the CRLF, but it is RECOMMENDED that lines be limited to 78 characters excluding the CRLF. (See section 2.1.1 for explanation.) In a message body, though all of the characters listed in the text rule MAY be used, the use of US-ASCII control characters (values 1 through 8, 11, 12, and 14 through 31) is discouraged since their interpretation by receivers for display is not guaranteed.
消息由头字段组成，可选地后跟消息正文。消息中的行数不得超过998个字符（不包括CRLF），但建议将行数限制为78个字符（不包括CRLF）。（有关说明，请参见第2.1.1节。）在消息正文中，尽管可以使用文本规则中列出的所有字符，但不鼓励使用US-ASCII控制字符（值1至8、11、12和14至31），因为无法保证接收者对其进行显示解释。
message = (fields / obs-fields)
[CRLF body]
message = (fields / obs-fields)
[CRLF body]
body = (*(*998text CRLF) *998text) / obs-body
body = (*(*998text CRLF) *998text) / obs-body
text = %d1-9 / ; Characters excluding CR
%d11 / ; and LF
%d12 /
%d14-127
text = %d1-9 / ; Characters excluding CR
%d11 / ; and LF
%d12 /
%d14-127
The header fields carry most of the semantic information and are defined in section 3.6. The body is simply a series of lines of text that are uninterpreted for the purposes of this specification.
标题字段包含大部分语义信息，在第3.6节中定义。正文只是本规范中未解释的一系列文本行。
The header fields of a message are defined here. All header fields have the same general syntactic structure: a field name, followed by a colon, followed by the field body. The specific syntax for each header field is defined in the subsequent sections.
此处定义了消息的标题字段。所有标题字段都具有相同的通用语法结构：字段名，后跟冒号，后跟字段正文。每个标题字段的特定语法将在后续章节中定义。
Note: In the ABNF syntax for each field in subsequent sections, each field name is followed by the required colon. However, for brevity, sometimes the colon is not referred to in the textual description of the syntax. It is, nonetheless, required.
注意：在后续章节中每个字段的ABNF语法中，每个字段名称后面都跟有所需的冒号。但是，为简洁起见，有时在语法的文本描述中不引用冒号。然而，这是必需的。
It is important to note that the header fields are not guaranteed to be in a particular order. They may appear in any order, and they have been known to be reordered occasionally when transported over the Internet. However, for the purposes of this specification, header fields SHOULD NOT be reordered when a message is transported or transformed. More importantly, the trace header fields and resent header fields MUST NOT be reordered, and SHOULD be kept in blocks prepended to the message. See sections 3.6.6 and 3.6.7 for more information.
需要注意的是，头字段不能保证按特定顺序排列。它们可能以任何顺序出现，并且已知在通过互联网传输时偶尔会重新排序。但是，出于本规范的目的，在传输或转换消息时，不应重新排序头字段。更重要的是，跟踪头字段和重新发送头字段不能重新排序，应该保留在消息前面的块中。详见第3.6.6节和第3.6.7节。
The only required header fields are the origination date field and the originator address field(s). All other header fields are syntactically optional. More information is contained in the table following this definition.
唯一需要的标题字段是“发起人日期”字段和“发起人地址”字段。所有其他标题字段在语法上都是可选的。此定义后面的表中包含更多信息。
fields = *(trace
*optional-field /
*(resent-date /
resent-from /
resent-sender /
resent-to /
resent-cc /
resent-bcc /
resent-msg-id))
*(orig-date /
from /
sender /
reply-to /
to /
cc /
bcc /
message-id /
in-reply-to /
references /
subject /
comments /
keywords /
optional-field)
fields = *(trace
*optional-field /
*(resent-date /
resent-from /
resent-sender /
resent-to /
resent-cc /
resent-bcc /
resent-msg-id))
*(orig-date /
from /
sender /
reply-to /
to /
cc /
bcc /
message-id /
in-reply-to /
references /
subject /
comments /
keywords /
optional-field)
The following table indicates limits on the number of times each field may occur in the header section of a message as well as any special limitations on the use of those fields. An asterisk ("*") next to a value in the minimum or maximum column indicates that a special restriction appears in the Notes column.
下表列出了对每个字段在消息头部分中出现的次数的限制，以及对这些字段的使用的任何特殊限制。最小值或最大值列中值旁边的星号（“*”）表示注释列中出现特殊限制。
+----------------+--------+------------+----------------------------+
| Field | Min | Max number | Notes |
| | number | | |
+----------------+--------+------------+----------------------------+
| trace | 0 | unlimited | Block prepended - see |
| | | | 3.6.7 |
| resent-date | 0* | unlimited* | One per block, required if |
| | | | other resent fields are |
| | | | present - see 3.6.6 |
| resent-from | 0 | unlimited* | One per block - see 3.6.6 |
| resent-sender | 0* | unlimited* | One per block, MUST occur |
| | | | with multi-address |
| | | | resent-from - see 3.6.6 |
| resent-to | 0 | unlimited* | One per block - see 3.6.6 |
| resent-cc | 0 | unlimited* | One per block - see 3.6.6 |
| resent-bcc | 0 | unlimited* | One per block - see 3.6.6 |
| resent-msg-id | 0 | unlimited* | One per block - see 3.6.6 |
| orig-date | 1 | 1 | |
| from | 1 | 1 | See sender and 3.6.2 |
| sender | 0* | 1 | MUST occur with |
| | | | multi-address from - see |
| | | | 3.6.2 |
| reply-to | 0 | 1 | |
| to | 0 | 1 | |
| cc | 0 | 1 | |
| bcc | 0 | 1 | |
| message-id | 0* | 1 | SHOULD be present - see |
| | | | 3.6.4 |
| in-reply-to | 0* | 1 | SHOULD occur in some |
| | | | replies - see 3.6.4 |
| references | 0* | 1 | SHOULD occur in some |
| | | | replies - see 3.6.4 |
| subject | 0 | 1 | |
| comments | 0 | unlimited | |
| keywords | 0 | unlimited | |
| optional-field | 0 | unlimited | |
+----------------+--------+------------+----------------------------+
+----------------+--------+------------+----------------------------+
| Field | Min | Max number | Notes |
| | number | | |
+----------------+--------+------------+----------------------------+
| trace | 0 | unlimited | Block prepended - see |
| | | | 3.6.7 |
| resent-date | 0* | unlimited* | One per block, required if |
| | | | other resent fields are |
| | | | present - see 3.6.6 |
| resent-from | 0 | unlimited* | One per block - see 3.6.6 |
| resent-sender | 0* | unlimited* | One per block, MUST occur |
| | | | with multi-address |
| | | | resent-from - see 3.6.6 |
| resent-to | 0 | unlimited* | One per block - see 3.6.6 |
| resent-cc | 0 | unlimited* | One per block - see 3.6.6 |
| resent-bcc | 0 | unlimited* | One per block - see 3.6.6 |
| resent-msg-id | 0 | unlimited* | One per block - see 3.6.6 |
| orig-date | 1 | 1 | |
| from | 1 | 1 | See sender and 3.6.2 |
| sender | 0* | 1 | MUST occur with |
| | | | multi-address from - see |
| | | | 3.6.2 |
| reply-to | 0 | 1 | |
| to | 0 | 1 | |
| cc | 0 | 1 | |
| bcc | 0 | 1 | |
| message-id | 0* | 1 | SHOULD be present - see |
| | | | 3.6.4 |
| in-reply-to | 0* | 1 | SHOULD occur in some |
| | | | replies - see 3.6.4 |
| references | 0* | 1 | SHOULD occur in some |
| | | | replies - see 3.6.4 |
| subject | 0 | 1 | |
| comments | 0 | unlimited | |
| keywords | 0 | unlimited | |
| optional-field | 0 | unlimited | |
+----------------+--------+------------+----------------------------+
The exact interpretation of each field is described in subsequent sections.
每个字段的准确解释将在后续章节中描述。
The origination date field consists of the field name "Date" followed by a date-time specification.
“起始日期”字段由字段名“日期”和日期时间规范组成。
orig-date = "Date:" date-time CRLF
orig date=“日期：”日期时间CRLF
The origination date specifies the date and time at which the creator of the message indicated that the message was complete and ready to enter the mail delivery system. For instance, this might be the time that a user pushes the "send" or "submit" button in an application program. In any case, it is specifically not intended to convey the time that the message is actually transported, but rather the time at which the human or other creator of the message has put the message into its final form, ready for transport. (For example, a portable computer user who is not connected to a network might queue a message for delivery. The origination date is intended to contain the date and time that the user queued the message, not the time when the user connected to the network to send the message.)
发起日期指定邮件创建者表示邮件已完成并准备好进入邮件传递系统的日期和时间。例如，这可能是用户在应用程序中按下“发送”或“提交”按钮的时间。在任何情况下，其具体目的不是传达消息实际被传输的时间，而是传达消息的人或其他创建者将消息放入其最终形式并准备好传输的时间。（例如，未连接到网络的便携式计算机用户可能会将邮件排队等待传递。起始日期旨在包含用户将邮件排队的日期和时间，而不是连接到网络以发送邮件的用户的时间。）
The originator fields of a message consist of the from field, the sender field (when applicable), and optionally the reply-to field. The from field consists of the field name "From" and a comma-separated list of one or more mailbox specifications. If the from field contains more than one mailbox specification in the mailbox-list, then the sender field, containing the field name "Sender" and a single mailbox specification, MUST appear in the message. In either case, an optional reply-to field MAY also be included, which contains the field name "Reply-To" and a comma-separated list of one or more addresses.
邮件的“发件人”字段包括“发件人”字段、“发件人”字段（如果适用）和“回复”字段（可选）。“发件人”字段由字段名“发件人”和一个或多个邮箱规范的逗号分隔列表组成。如果“发件人”字段在邮箱列表中包含多个邮箱规范，则包含字段名“发件人”和单个邮箱规范的发件人字段必须出现在邮件中。在任何一种情况下，都可能包含一个可选的回复字段，其中包含字段名“回复”和一个或多个地址的逗号分隔列表。
from = "From:" mailbox-list CRLF
from=“from:”邮箱列表CRLF
sender = "Sender:" mailbox CRLF
发件人=“发件人：”邮箱CRLF
reply-to = "Reply-To:" address-list CRLF
回复至=“回复至：”地址列表CRLF
The originator fields indicate the mailbox(es) of the source of the message. The "From:" field specifies the author(s) of the message, that is, the mailbox(es) of the person(s) or system(s) responsible for the writing of the message. The "Sender:" field specifies the mailbox of the agent responsible for the actual transmission of the message. For example, if a secretary were to send a message for another person, the mailbox of the secretary would appear in the "Sender:" field and the mailbox of the actual author would appear in the "From:" field. If the originator of the message can be indicated
“原始发件人”字段表示邮件源的邮箱。“发件人：”字段指定邮件的作者，即负责撰写邮件的人员或系统的邮箱。“发件人：”字段指定负责实际传输邮件的代理的邮箱。例如，如果秘书要为另一个人发送邮件，则秘书的邮箱将显示在“发件人：”字段中，而实际作者的邮箱将显示在“发件人：”字段中。如果可以指明消息的发起人
by a single mailbox and the author and transmitter are identical, the "Sender:" field SHOULD NOT be used. Otherwise, both fields SHOULD appear.
如果一个邮箱的作者和发送者相同，则不应使用“发件人：”字段。否则，两个字段都应显示。
Note: The transmitter information is always present. The absence of the "Sender:" field is sometimes mistakenly taken to mean that the agent responsible for transmission of the message has not been specified. This absence merely means that the transmitter is identical to the author and is therefore not redundantly placed into the "Sender:" field.
注：变送器信息始终存在。缺少“Sender:”字段有时会被误认为意味着没有指定负责传输消息的代理。这种缺失仅仅意味着发送者与作者相同，因此不会冗余地放入“发送者：”字段。
The originator fields also provide the information required when replying to a message. When the "Reply-To:" field is present, it indicates the address(es) to which the author of the message suggests that replies be sent. In the absence of the "Reply-To:" field, replies SHOULD by default be sent to the mailbox(es) specified in the "From:" field unless otherwise specified by the person composing the reply.
“发件人”字段还提供回复邮件时所需的信息。当“回复：”字段存在时，它表示邮件作者建议向其发送回复的地址。如果没有“回复至：”字段，则默认情况下，回复应发送至“发件人：”字段中指定的邮箱，除非撰写回复的人员另有指定。
In all cases, the "From:" field SHOULD NOT contain any mailbox that does not belong to the author(s) of the message. See also section 3.6.3 for more information on forming the destination addresses for a reply.
在所有情况下，“发件人：”字段不应包含任何不属于邮件作者的邮箱。另请参见第3.6.3节，了解有关形成回复目的地地址的更多信息。
The destination fields of a message consist of three possible fields, each of the same form: the field name, which is either "To", "Cc", or "Bcc", followed by a comma-separated list of one or more addresses (either mailbox or group syntax).
邮件的目标字段由三个可能的字段组成，每个字段的形式相同：字段名，即“收件人”、“抄送”或“密件抄送”，后跟一个或多个地址的逗号分隔列表（邮箱或组语法）。
to = "To:" address-list CRLF
to=“to:”地址列表CRLF
cc = "Cc:" address-list CRLF
cc=“cc:”地址列表CRLF
bcc = "Bcc:" [address-list / CFWS] CRLF
bcc = "Bcc:" [address-list / CFWS] CRLF
The destination fields specify the recipients of the message. Each destination field may have one or more addresses, and the addresses indicate the intended recipients of the message. The only difference between the three fields is how each is used.
目标字段指定邮件的收件人。每个目的地字段可以有一个或多个地址，这些地址指示消息的预期收件人。这三个字段之间的唯一区别是如何使用它们。
The "To:" field contains the address(es) of the primary recipient(s) of the message.
“收件人：”字段包含邮件主要收件人的地址。
The "Cc:" field (where the "Cc" means "Carbon Copy" in the sense of making a copy on a typewriter using carbon paper) contains the addresses of others who are to receive the message, though the content of the message may not be directed at them.
“抄送：”字段（其中“抄送”在使用复写纸在打字机上制作副本的意义上是指“复写副本”）包含接收邮件的其他人的地址，尽管邮件的内容可能不针对他们。
The "Bcc:" field (where the "Bcc" means "Blind Carbon Copy") contains addresses of recipients of the message whose addresses are not to be revealed to other recipients of the message. There are three ways in which the "Bcc:" field is used. In the first case, when a message containing a "Bcc:" field is prepared to be sent, the "Bcc:" line is removed even though all of the recipients (including those specified in the "Bcc:" field) are sent a copy of the message. In the second case, recipients specified in the "To:" and "Cc:" lines each are sent a copy of the message with the "Bcc:" line removed as above, but the recipients on the "Bcc:" line get a separate copy of the message containing a "Bcc:" line. (When there are multiple recipient addresses in the "Bcc:" field, some implementations actually send a separate copy of the message to each recipient with a "Bcc:" containing only the address of that particular recipient.) Finally, since a "Bcc:" field may contain no addresses, a "Bcc:" field can be sent without any addresses indicating to the recipients that blind copies were sent to someone. Which method to use with "Bcc:" fields is implementation dependent, but refer to the "Security Considerations" section of this document for a discussion of each.
“密件抄送：”字段（其中“密件抄送”表示“盲拷贝”）包含邮件收件人的地址，这些收件人的地址不会透露给邮件的其他收件人。“密件抄送：”字段有三种使用方式。在第一种情况下，当准备发送包含“密件抄送：”字段的邮件时，“密件抄送：”行将被删除，即使所有收件人（包括“密件抄送：”字段中指定的收件人）都已发送邮件的副本。在第二种情况下，“收件人：”和“抄送：”行中指定的收件人将收到一份邮件的副本，其中“密件抄送：”行已如上所述删除，但“密件抄送：”行中的收件人将收到一份包含“密件抄送：”行的邮件的单独副本。（当“密件抄送：”字段中有多个收件人地址时，某些实现实际上会向每个收件人发送一份单独的邮件副本，其中“密件抄送：”仅包含该特定收件人的地址。）最后，由于“密件抄送：”字段可能不包含地址，“密件抄送”：字段可以在没有任何地址的情况下发送，该地址向收件人指示盲拷贝已发送给某人。“Bcc:”字段使用哪种方法取决于实现，但有关每种方法的讨论，请参阅本文档的“安全注意事项”部分。
When a message is a reply to another message, the mailboxes of the authors of the original message (the mailboxes in the "From:" field) or mailboxes specified in the "Reply-To:" field (if it exists) MAY appear in the "To:" field of the reply since these would normally be the primary recipients of the reply. If a reply is sent to a message that has destination fields, it is often desirable to send a copy of the reply to all of the recipients of the message, in addition to the author. When such a reply is formed, addresses in the "To:" and "Cc:" fields of the original message MAY appear in the "Cc:" field of the reply, since these are normally secondary recipients of the reply. If a "Bcc:" field is present in the original message, addresses in that field MAY appear in the "Bcc:" field of the reply, but they SHOULD NOT appear in the "To:" or "Cc:" fields.
当一封邮件是对另一封邮件的回复时，原始邮件作者的邮箱（“发件人：”字段中的邮箱）或“回复收件人：”字段中指定的邮箱（如果存在）可能会出现在回复的“收件人：”字段中，因为这些邮箱通常是回复的主要收件人。如果将回复发送到具有目标字段的邮件，则通常需要将回复的副本发送给邮件的所有收件人，以及作者。形成此类回复时，原始邮件的“收件人：”和“抄送：”字段中的地址可能会出现在回复的“抄送：”字段中，因为这些地址通常是回复的次要收件人。如果原始邮件中存在“密件抄送：”字段，则该字段中的地址可能会出现在回复的“密件抄送：”字段中，但不应出现在“收件人：”或“抄送：”字段中。
Note: Some mail applications have automatic reply commands that include the destination addresses of the original message in the destination addresses of the reply. How those reply commands behave is implementation dependent and is beyond the scope of this document. In particular, whether or not to include the original destination addresses when the original message had a "Reply-To:" field is not addressed here.
注意：某些邮件应用程序具有自动回复命令，该命令在回复的目标地址中包含原始邮件的目标地址。这些回复命令的行为取决于实现，不在本文档的范围之内。特别是，当原始邮件有“回复：”字段时，是否包括原始目的地地址不在此处。
Though listed as optional in the table in section 3.6, every message SHOULD have a "Message-ID:" field. Furthermore, reply messages SHOULD have "In-Reply-To:" and "References:" fields as appropriate and as described below.
尽管在第3.6节的表格中列为可选，但每条消息都应该有一个“消息ID:”字段。此外，回复消息应具有“回复中：”和“引用：”字段（视情况而定），如下所述。
The "Message-ID:" field contains a single unique message identifier. The "References:" and "In-Reply-To:" fields each contain one or more unique message identifiers, optionally separated by CFWS.
“消息ID:”字段包含一个唯一的消息标识符。“References:”和“Reply To:”字段中的每个字段都包含一个或多个唯一的消息标识符，可以选择用CFW分隔。
The message identifier (msg-id) syntax is a limited version of the addr-spec construct enclosed in the angle bracket characters, "<" and ">". Unlike addr-spec, this syntax only permits the dot-atom-text form on the left-hand side of the "@" and does not have internal CFWS anywhere in the message identifier.
消息标识符（msg id）语法是addr spec构造的有限版本，包含在尖括号字符“<”和“>”中。与addr spec不同，此语法只允许在“@”的左侧使用点原子文本形式，并且在消息标识符中的任何位置都没有内部CFW。
Note: As with addr-spec, a liberal syntax is given for the right-hand side of the "@" in a msg-id. However, later in this section, the use of a domain for the right-hand side of the "@" is RECOMMENDED. Again, the syntax of domain constructs is specified by and used in other protocols (e.g., [RFC1034], [RFC1035], [RFC1123], [RFC5321]). It is therefore incumbent upon implementations to conform to the syntax of addresses for the context in which they are used.
注意：与addr spec一样，msg-id中“@”的右侧使用了宽松的语法。但是，在本节后面，建议在“@”的右侧使用域。同样，域构造的语法由其他协议（例如，[RFC1034]、[RFC1035]、[RFC1123]、[RFC5321]）指定并在其中使用。因此，实现必须遵守使用地址的上下文的地址语法。
message-id = "Message-ID:" msg-id CRLF
message id=“message id:”消息id CRLF
in-reply-to = "In-Reply-To:" 1*msg-id CRLF
in-reply-to = "In-Reply-To:" 1*msg-id CRLF
references = "References:" 1*msg-id CRLF
references = "References:" 1*msg-id CRLF
msg-id = [CFWS] "<" id-left "@" id-right ">" [CFWS]
msg-id = [CFWS] "<" id-left "@" id-right ">" [CFWS]
id-left = dot-atom-text / obs-id-left
id-left = dot-atom-text / obs-id-left
id-right = dot-atom-text / no-fold-literal / obs-id-right
id-right = dot-atom-text / no-fold-literal / obs-id-right
no-fold-literal = "[" *dtext "]"
无折叠文字=“[”*dtext”]”
The "Message-ID:" field provides a unique message identifier that refers to a particular version of a particular message. The uniqueness of the message identifier is guaranteed by the host that generates it (see below). This message identifier is intended to be machine readable and not necessarily meaningful to humans. A message identifier pertains to exactly one version of a particular message; subsequent revisions to the message each receive new message identifiers.
“消息ID:”字段提供一个唯一的消息标识符，该标识符表示特定消息的特定版本。消息标识符的唯一性由生成它的主机保证（见下文）。该消息标识符是机器可读的，不一定对人类有意义。消息标识符仅与特定消息的一个版本相关；消息的后续修订都会接收新的消息标识符。
Note: There are many instances when messages are "changed", but those changes do not constitute a new instantiation of that message, and therefore the message would not get a new message identifier. For example, when messages are introduced into the transport system, they are often prepended with additional header fields such as trace fields (described in section 3.6.7) and resent fields (described in section 3.6.6). The addition of such header fields does not change the identity of the message and therefore the original "Message-ID:" field is retained. In all cases, it is the meaning that the sender of the message wishes to convey (i.e., whether this is the same message or a different message) that determines whether or not the "Message-ID:" field changes, not any particular syntactic difference that appears (or does not appear) in the message.
注意：消息“更改”时有许多实例，但这些更改并不构成该消息的新实例化，因此该消息不会获得新的消息标识符。例如，当消息被引入传输系统时，它们通常带有附加的头字段，如跟踪字段（如第3.6.7节所述）和重新发送字段（如第3.6.6节所述）。添加此类标头字段不会更改消息的标识，因此保留原始的“消息ID:”字段。在所有情况下，消息发送者希望传达的含义（即，这是相同的消息还是不同的消息）决定“消息ID:”字段是否更改，而不是消息中出现（或未出现）的任何特定语法差异。
The "In-Reply-To:" and "References:" fields are used when creating a reply to a message. They hold the message identifier of the original message and the message identifiers of other messages (for example, in the case of a reply to a message that was itself a reply). The "In-Reply-To:" field may be used to identify the message (or messages) to which the new message is a reply, while the "References:" field may be used to identify a "thread" of conversation.
“回复：”和“引用：”字段在创建邮件回复时使用。它们保存原始消息的消息标识符和其他消息的消息标识符（例如，在对消息本身就是应答的应答的情况下）。“In Reply To:”字段可用于标识新消息作为回复的消息，而“References:”字段可用于标识对话的“线程”。
When creating a reply to a message, the "In-Reply-To:" and "References:" fields of the resultant message are constructed as follows:
创建邮件回复时，结果邮件的“回复中：”和“引用：”字段的构造如下：
The "In-Reply-To:" field will contain the contents of the "Message-ID:" field of the message to which this one is a reply (the "parent message"). If there is more than one parent message, then the "In-Reply-To:" field will contain the contents of all of the parents' "Message-ID:" fields. If there is no "Message-ID:" field in any of the parent messages, then the new message will have no "In-Reply-To:" field.
“回复到：”字段将包含作为回复的消息（“父消息”）的“消息ID:”字段的内容。如果有多个父消息，“回复：”字段将包含所有父消息“消息ID:”字段的内容。如果任何父消息中都没有“消息ID:”字段，则新消息将没有“回复：”字段。
The "References:" field will contain the contents of the parent's "References:" field (if any) followed by the contents of the parent's "Message-ID:" field (if any). If the parent message does not contain a "References:" field but does have an "In-Reply-To:" field containing a single message identifier, then the "References:" field will contain the contents of the parent's "In-Reply-To:" field followed by the contents of the parent's "Message-ID:" field (if any). If the parent has none of the "References:", "In-Reply-To:", or "Message-ID:" fields, then the new message will have no "References:" field.
“References:”字段将包含父级的“References:”字段（如果有）的内容，后跟父级的“Message ID:”字段（如果有）的内容。如果父消息不包含“References:”字段，但有一个“In Reply To:”字段，该字段包含单个消息标识符，则“References:”字段将包含父消息的内容，然后是父消息的“message ID:”字段的内容（如果有）。如果父级没有“References:”、“In Reply To:”或“Message ID:”字段，则新消息将没有“References:”字段。
Note: Some implementations parse the "References:" field to display the "thread of the discussion". These implementations assume that each new message is a reply to a single parent and hence that they can walk backwards through the "References:" field to find the parent of each message listed there. Therefore, trying to form a "References:" field for a reply that has multiple parents is discouraged; how to do so is not defined in this document.
注意：一些实现解析“References:”字段以显示“讨论线程”。这些实现假设每一条新消息都是对单个父消息的回复，因此它们可以向后遍历“References:”字段以查找其中列出的每条消息的父消息。因此，不鼓励尝试为具有多个父级的回复形成“References:”字段；如何做到这一点在本文件中没有定义。
The message identifier (msg-id) itself MUST be a globally unique identifier for a message. The generator of the message identifier MUST guarantee that the msg-id is unique. There are several algorithms that can be used to accomplish this. Since the msg-id has a similar syntax to addr-spec (identical except that quoted strings, comments, and folding white space are not allowed), a good method is to put the domain name (or a domain literal IP address) of the host on which the message identifier was created on the right-hand side of the "@" (since domain names and IP addresses are normally unique), and put a combination of the current absolute date and time along with some other currently unique (perhaps sequential) identifier available on the system (for example, a process id number) on the left-hand side. Though other algorithms will work, it is RECOMMENDED that the right-hand side contain some domain identifier (either of the host itself or otherwise) such that the generator of the message identifier can guarantee the uniqueness of the left-hand side within the scope of that domain.
消息标识符（msg id）本身必须是消息的全局唯一标识符。消息标识符的生成器必须保证消息id是唯一的。有几种算法可以用来实现这一点。由于msg id的语法与addr spec类似（除了不允许使用带引号的字符串、注释和折叠空格外，其他语法相同），因此最好将创建消息标识符的主机的域名（或域文字IP地址）放在“@”的右侧（因为域名和IP地址通常是唯一的），并将当前绝对日期和时间与系统上可用的其他当前唯一（可能是顺序）标识符（例如，进程id号）组合在一起在左侧。虽然其他算法也可以工作，但建议右侧包含一些域标识符（主机本身或其他），以便消息标识符的生成器可以保证左侧在该域范围内的唯一性。
Semantically, the angle bracket characters are not part of the msg-id; the msg-id is what is contained between the two angle bracket characters.
从语义上讲，尖括号字符不是msg id的一部分；msg id包含在两个尖括号字符之间。
The informational fields are all optional. The "Subject:" and "Comments:" fields are unstructured fields as defined in section 2.2.1, and therefore may contain text or folding white space. The "Keywords:" field contains a comma-separated list of one or more words or quoted-strings.
信息字段都是可选的。“主题：”和“注释：”字段是第2.2.1节中定义的非结构化字段，因此可能包含文本或折叠空白。“关键字：”字段包含一个或多个单词或带引号字符串的逗号分隔列表。
subject = "Subject:" unstructured CRLF
subject=“subject:“非结构化CRLF”
comments = "Comments:" unstructured CRLF
comments=“comments:”非结构化CRLF
keywords = "Keywords:" phrase *("," phrase) CRLF
keywords = "Keywords:" phrase *("," phrase) CRLF
These three fields are intended to have only human-readable content with information about the message. The "Subject:" field is the most common and contains a short string identifying the topic of the
这三个字段的目的是仅包含人类可读的内容以及有关消息的信息。“主题：”字段是最常见的字段，它包含一个识别主题的短字符串
message. When used in a reply, the field body MAY start with the string "Re: " (an abbreviation of the Latin "in re", meaning "in the matter of") followed by the contents of the "Subject:" field body of the original message. If this is done, only one instance of the literal string "Re: " ought to be used since use of other strings or more than one instance can lead to undesirable consequences. The "Comments:" field contains any additional comments on the text of the body of the message. The "Keywords:" field contains a comma-separated list of important words and phrases that might be useful for the recipient.
消息在回复中使用时，字段正文可以以字符串“Re:”（拉丁语“in Re”的缩写，意思是“in the matter of”）开头，然后是原始消息的“Subject:”字段正文的内容。如果这样做，则只应使用文字字符串“Re:”的一个实例，因为使用其他字符串或多个实例可能会导致不良后果。“评论：”字段包含对消息正文文本的任何附加评论。“关键字：”字段包含一个逗号分隔的重要单词和短语列表，这些单词和短语可能对收件人有用。
Resent fields SHOULD be added to any message that is reintroduced by a user into the transport system. A separate set of resent fields SHOULD be added each time this is done. All of the resent fields corresponding to a particular resending of the message SHOULD be grouped together. Each new set of resent fields is prepended to the message; that is, the most recent set of resent fields appears earlier in the message. No other fields in the message are changed when resent fields are added.
重新发送字段应添加到用户重新引入传输系统的任何消息中。每次执行此操作时，应添加一组单独的重新发送字段。与消息的特定重新发送相对应的所有重新发送字段应分组在一起。每一组新的重新发送字段都在消息的前面；也就是说，最新的一组“重新发送”字段出现在消息的前面。添加“重新发送”字段时，不会更改消息中的其他字段。
Each of the resent fields corresponds to a particular field elsewhere in the syntax. For instance, the "Resent-Date:" field corresponds to the "Date:" field and the "Resent-To:" field corresponds to the "To:" field. In each case, the syntax for the field body is identical to the syntax given previously for the corresponding field.
每个resent字段都对应于语法中其他位置的特定字段。例如，“重新发送日期：”字段对应于“日期：”字段，“重新发送至：”字段对应于“收件人：”字段。在每种情况下，字段正文的语法都与前面为相应字段给出的语法相同。
When resent fields are used, the "Resent-From:" and "Resent-Date:" fields MUST be sent. The "Resent-Message-ID:" field SHOULD be sent. "Resent-Sender:" SHOULD NOT be used if "Resent-Sender:" would be identical to "Resent-From:".
使用“重新发送”字段时，必须发送“重新发送自：”和“重新发送日期：”字段。应发送“重新发送消息ID:”字段。如果“Resent Sender:”与“Resent From:”相同，则不应使用“Resent Sender:”。
resent-date = "Resent-Date:" date-time CRLF
重新发送日期=“重新发送日期：”日期时间CRLF
resent-from = "Resent-From:" mailbox-list CRLF
resent from=“resent from:”邮箱列表CRLF
resent-sender = "Resent-Sender:" mailbox CRLF
重新发送发件人=“重新发送发件人：”邮箱CRLF
resent-to = "Resent-To:" address-list CRLF
重新发送至=“重新发送至：”地址列表CRLF
resent-cc = "Resent-Cc:" address-list CRLF
resent cc=“resent cc:”地址列表CRLF
resent-bcc = "Resent-Bcc:" [address-list / CFWS] CRLF
resent-bcc = "Resent-Bcc:" [address-list / CFWS] CRLF
resent-msg-id = "Resent-Message-ID:" msg-id CRLF
重新发送消息id=“重新发送消息id:”消息id CRLF
Resent fields are used to identify a message as having been reintroduced into the transport system by a user. The purpose of using resent fields is to have the message appear to the final recipient as if it were sent directly by the original sender, with all of the original fields remaining the same. Each set of resent fields correspond to a particular resending event. That is, if a message is resent multiple times, each set of resent fields gives identifying information for each individual time. Resent fields are strictly informational. They MUST NOT be used in the normal processing of replies or other such automatic actions on messages.
“重新发送”字段用于标识已由用户重新引入传输系统的消息。使用“重新发送”字段的目的是使邮件在最终收件人面前显示为原始发件人直接发送的邮件，所有原始字段保持不变。每组重新发送字段对应于特定的重新发送事件。也就是说，如果一条消息被多次重新发送，则每组重新发送字段将给出每个单独时间的标识信息。Resent字段是严格的信息字段。它们不得用于回复的正常处理或对邮件的其他此类自动操作。
Note: Reintroducing a message into the transport system and using resent fields is a different operation from "forwarding". "Forwarding" has two meanings: One sense of forwarding is that a mail reading program can be told by a user to forward a copy of a message to another person, making the forwarded message the body of the new message. A forwarded message in this sense does not appear to have come from the original sender, but is an entirely new message from the forwarder of the message. Forwarding may also mean that a mail transport program gets a message and forwards it on to a different destination for final delivery. Resent header fields are not intended for use with either type of forwarding.
注意：将消息重新引入传输系统并使用重新发送字段与“转发”操作不同。“转发”有两种含义：转发的一种含义是，用户可以告诉邮件阅读程序将邮件副本转发给另一个人，使转发的邮件成为新邮件的主体。从这个意义上讲，转发的消息似乎不是来自原始发件人，而是来自消息转发器的全新消息。转发也可能意味着邮件传输程序获取一条消息并将其转发到另一个目的地进行最终传递。“重新发送头”字段不适用于任何类型的转发。
The resent originator fields indicate the mailbox of the person(s) or system(s) that resent the message. As with the regular originator fields, there are two forms: a simple "Resent-From:" form, which contains the mailbox of the individual doing the resending, and the more complex form, when one individual (identified in the "Resent-Sender:" field) resends a message on behalf of one or more others (identified in the "Resent-From:" field).
“重新发送发件人”字段表示重新发送邮件的人员或系统的邮箱。与常规的“发件人”字段一样，有两种形式：一种是简单的“重新发送发件人：”形式，其中包含进行重新发送的个人的邮箱；另一种是更复杂的形式，当一个人（在“重新发送发件人：”字段中标识）代表一个或多个其他人（在“重新发送发件人：”字段中标识）重新发送邮件时。
Note: When replying to a resent message, replies behave just as they would with any other message, using the original "From:", "Reply-To:", "Message-ID:", and other fields. The resent fields are only informational and MUST NOT be used in the normal processing of replies.
注意：回复重新发送的邮件时，使用原始的“发件人：”、“回复收件人：”、“邮件ID:”和其他字段，回复的行为与其他任何邮件一样。“重新发送”字段仅供参考，不能用于回复的正常处理。
The "Resent-Date:" indicates the date and time at which the resent message is dispatched by the resender of the message. Like the "Date:" field, it is not the date and time that the message was actually transported.
“重新发送日期：”表示重新发送邮件的发件人发送重新发送邮件的日期和时间。与“日期：”字段类似，它不是消息实际传输的日期和时间。
The "Resent-To:", "Resent-Cc:", and "Resent-Bcc:" fields function identically to the "To:", "Cc:", and "Bcc:" fields, respectively, except that they indicate the recipients of the resent message, not the recipients of the original message.
“重新发送到：”、“重新发送抄送：”、“重新发送密件抄送：”字段的功能分别与“发送到：”、“抄送：”、“密件抄送：”字段的功能相同，只是它们表示重新发送邮件的收件人，而不是原始邮件的收件人。
The "Resent-Message-ID:" field provides a unique identifier for the resent message.
“重新发送消息ID:”字段为重新发送消息提供唯一标识符。
The trace fields are a group of header fields consisting of an optional "Return-Path:" field, and one or more "Received:" fields. The "Return-Path:" header field contains a pair of angle brackets that enclose an optional addr-spec. The "Received:" field contains a (possibly empty) list of tokens followed by a semicolon and a date-time specification. Each token must be a word, angle-addr, addr-spec, or a domain. Further restrictions are applied to the syntax of the trace fields by specifications that provide for their use, such as [RFC5321].
跟踪字段是一组标题字段，由可选的“返回路径：”字段和一个或多个“已接收：”字段组成。“Return Path:”标题字段包含一对尖括号，其中包含可选的addr-spec。“Received:”字段包含令牌列表（可能为空），后跟分号和日期时间规范。每个令牌必须是单词、角度地址、地址规范或域。通过提供跟踪字段使用的规范（如[RFC5321]）对跟踪字段的语法应用了进一步的限制。
trace = [return]
1*received
trace = [return]
1*received
return = "Return-Path:" path CRLF
return=“返回路径：”路径CRLF
path = angle-addr / ([CFWS] "<" [CFWS] ">" [CFWS])
path = angle-addr / ([CFWS] "<" [CFWS] ">" [CFWS])
received = "Received:" *received-token ";" date-time CRLF
received = "Received:" *received-token ";" date-time CRLF
received-token = word / angle-addr / addr-spec / domain
received-token = word / angle-addr / addr-spec / domain
A full discussion of the Internet mail use of trace fields is contained in [RFC5321]. For the purposes of this specification, the trace fields are strictly informational, and any formal interpretation of them is outside of the scope of this document.
[RFC5321]中包含了有关Internet邮件使用跟踪字段的完整讨论。出于本规范的目的，跟踪字段是严格的信息性字段，对它们的任何正式解释都不在本文档的范围之内。
Fields may appear in messages that are otherwise unspecified in this document. They MUST conform to the syntax of an optional-field. This is a field name, made up of the printable US-ASCII characters except SP and colon, followed by a colon, followed by any text that conforms to the unstructured syntax.
字段可能出现在本文档中未指定的消息中。它们必须符合可选字段的语法。这是一个字段名，由除SP和冒号之外的可打印US-ASCII字符组成，后跟冒号，后跟符合非结构化语法的任何文本。
The field names of any optional field MUST NOT be identical to any field name specified elsewhere in this document.
任何可选字段的字段名不得与本文档其他地方指定的任何字段名相同。
optional-field = field-name ":" unstructured CRLF
可选字段=字段名“：“非结构化CRLF”
field-name = 1*ftext
field-name = 1*ftext
ftext = %d33-57 / ; Printable US-ASCII
%d59-126 ; characters not including
; ":".
ftext = %d33-57 / ; Printable US-ASCII
%d59-126 ; characters not including
; ":".
For the purposes of this specification, any optional field is uninterpreted.
在本规范中，任何可选字段均不解释。
Earlier versions of this specification allowed for different (usually more liberal) syntax than is allowed in this version. Also, there have been syntactic elements used in messages on the Internet whose interpretations have never been documented. Though these syntactic forms MUST NOT be generated according to the grammar in section 3, they MUST be accepted and parsed by a conformant receiver. This section documents many of these syntactic elements. Taking the grammar in section 3 and adding the definitions presented in this section will result in the grammar to use for the interpretation of messages.
本规范的早期版本允许使用不同于本版本的语法（通常更自由）。此外，互联网上的信息中使用了一些句法元素，其解释从未被记录下来。尽管这些句法形式不能根据第3节中的语法生成，但它们必须被一致的接收者接受和解析。本节记录了其中许多语法元素。采用第3节中的语法并添加本节中给出的定义将产生用于解释消息的语法。
Note: This section identifies syntactic forms that any implementation MUST reasonably interpret. However, there are certainly Internet messages that do not conform to even the additional syntax given in this section. The fact that a particular form does not appear in any section of this document is not justification for computer programs to crash or for malformed data to be irretrievably lost by any implementation. It is up to the implementation to deal with messages robustly.
注意：本节确定了任何实现都必须合理解释的语法形式。但是，肯定有一些互联网消息甚至不符合本节中给出的附加语法。本文档任何部分中未出现特定表单这一事实并不是计算机程序崩溃或错误数据因任何实现而无法挽回地丢失的理由。由实现可靠地处理消息。
One important difference between the obsolete (interpreting) and the current (generating) syntax is that in structured header field bodies (i.e., between the colon and the CRLF of any structured header field), white space characters, including folding white space, and comments could be freely inserted between any syntactic tokens. This allowed many complex forms that have proven difficult for some implementations to parse.
过时（解释）和当前（生成）语法之间的一个重要区别是，在结构化标题字段正文中（即，任何结构化标题字段的冒号和CRLF之间），空白字符（包括折叠空白）和注释可以自由插入任何语法标记之间。这使得许多复杂的表单很难被某些实现解析。
Another key difference between the obsolete and the current syntax is that the rule in section 3.2.2 regarding lines composed entirely of white space in comments and folding white space does not apply. See the discussion of folding white space in section 4.2 below.
过时语法和当前语法之间的另一个关键区别是，第3.2.2节中关于注释中完全由空格和折叠空格组成的行的规则不适用。请参见下面第4.2节中关于折叠空白的讨论。
Finally, certain characters that were formerly allowed in messages appear in this section. The NUL character (ASCII value 0) was once
最后，此部分显示以前允许在消息中使用的某些字符。NUL字符（ASCII值为0）被删除一次
allowed, but is no longer for compatibility reasons. Similarly, US-ASCII control characters other than CR, LF, SP, and HTAB (ASCII values 1 through 8, 11, 12, 14 through 31, and 127) were allowed to appear in header field bodies. CR and LF were allowed to appear in messages other than as CRLF; this use is also shown here.
允许，但出于兼容性原因不再允许。同样，除了CR、LF、SP和HTAB（ASCII值1到8、11、12、14到31和127）之外的US-ASCII控制字符也允许出现在标题字段体中。允许CR和LF以CRLF以外的形式出现在消息中；这里也显示了这种用法。
Other differences in syntax and semantics are noted in the following sections.
语法和语义上的其他差异在以下部分中有所说明。
These syntactic elements are used elsewhere in the obsolete syntax or in the main syntax. Bare CR, bare LF, and NUL are added to obs-qp, obs-body, and obs-unstruct. US-ASCII control characters are added to obs-qp, obs-unstruct, obs-ctext, and obs-qtext. The period character is added to obs-phrase. The obs-phrase-list provides for a (potentially empty) comma-separated list of phrases that may include "null" elements. That is, there could be two or more commas in such a list with nothing in between them, or commas at the beginning or end of the list.
这些语法元素在过时语法或主语法中的其他位置使用。裸CR、裸LF和NUL被添加到obs qp、obs body和obs unstruct中。将US-ASCII控制字符添加到obs qp、obs unstruct、obs ctext和obs qtext中。周期字符将添加到obs短语中。obs短语列表提供了一个（可能为空）逗号分隔的短语列表，其中可能包含“null”元素。也就是说，在这样一个列表中可能有两个或多个逗号，它们之间没有任何内容，或者在列表的开头或结尾有逗号。
Note: The "period" (or "full stop") character (".") in obs-phrase is not a form that was allowed in earlier versions of this or any other specification. Period (nor any other character from specials) was not allowed in phrase because it introduced a parsing difficulty distinguishing between phrases and portions of an addr-spec (see section 4.4). It appears here because the period character is currently used in many messages in the display-name portion of addresses, especially for initials in names, and therefore must be interpreted properly.
注意：obs短语中的“句号”（或“句号”）字符（“.”）不是本规范或任何其他规范早期版本中允许的格式。短语中不允许使用句点（也不允许使用特殊字符中的任何其他字符），因为句点会导致语法分析困难，难以区分短语和addr规范的各个部分（请参见第4.4节）。之所以出现在这里，是因为当前在地址的显示名称部分的许多消息中使用句点字符，尤其是名称中的首字母，因此必须正确解释。
obs-NO-WS-CTL = %d1-8 / ; US-ASCII control
%d11 / ; characters that do not
%d12 / ; include the carriage
%d14-31 / ; return, line feed, and
%d127 ; white space characters
obs-NO-WS-CTL = %d1-8 / ; US-ASCII control
%d11 / ; characters that do not
%d12 / ; include the carriage
%d14-31 / ; return, line feed, and
%d127 ; white space characters
obs-ctext = obs-NO-WS-CTL
obs-ctext = obs-NO-WS-CTL
obs-qtext = obs-NO-WS-CTL
obs-qtext = obs-NO-WS-CTL
obs-utext = %d0 / obs-NO-WS-CTL / VCHAR
obs-utext = %d0 / obs-NO-WS-CTL / VCHAR
obs-qp = "\" (%d0 / obs-NO-WS-CTL / LF / CR)
obs-qp = "\" (%d0 / obs-NO-WS-CTL / LF / CR)
obs-body = *((*LF *CR *((%d0 / text) *LF *CR)) / CRLF)
obs-body = *((*LF *CR *((%d0 / text) *LF *CR)) / CRLF)
obs-unstruct = *((*LF *CR *(obs-utext *LF *CR)) / FWS)
obs-unstruct = *((*LF *CR *(obs-utext *LF *CR)) / FWS)
obs-phrase = word *(word / "." / CFWS)
obs-phrase = word *(word / "." / CFWS)
obs-phrase-list = [phrase / CFWS] *("," [phrase / CFWS])
obs-phrase-list = [phrase / CFWS] *("," [phrase / CFWS])
Bare CR and bare LF appear in messages with two different meanings. In many cases, bare CR or bare LF are used improperly instead of CRLF to indicate line separators. In other cases, bare CR and bare LF are used simply as US-ASCII control characters with their traditional ASCII meanings.
Bare CR和Bare LF出现在具有两种不同含义的消息中。在许多情况下，不正确地使用裸CR或裸LF代替CRLF来指示线路分离器。在其他情况下，bare CR和bare LF仅用作具有传统ASCII含义的US-ASCII控制字符。
In the obsolete syntax, any amount of folding white space MAY be inserted where the obs-FWS rule is allowed. This creates the possibility of having two consecutive "folds" in a line, and therefore the possibility that a line which makes up a folded header field could be composed entirely of white space.
在过时的语法中，可以在允许obs FWS规则的地方插入任意数量的折叠空白。这就产生了在一行中有两个连续“折叠”的可能性，因此构成折叠标题字段的行可能完全由空白组成。
obs-FWS = 1*WSP *(CRLF 1*WSP)
obs-FWS = 1*WSP *(CRLF 1*WSP)
The syntax for the obsolete date format allows a 2 digit year in the date field and allows for a list of alphabetic time zone specifiers that were used in earlier versions of this specification. It also permits comments and folding white space between many of the tokens.
过时日期格式的语法允许在日期字段中使用2位数的年份，并允许在此规范早期版本中使用的字母时区说明符列表。它还允许在许多标记之间添加注释和折叠空格。
obs-day-of-week = [CFWS] day-name [CFWS]
obs-day-of-week = [CFWS] day-name [CFWS]
obs-day = [CFWS] 1*2DIGIT [CFWS]
obs-day = [CFWS] 1*2DIGIT [CFWS]
obs-year = [CFWS] 2*DIGIT [CFWS]
obs-year = [CFWS] 2*DIGIT [CFWS]
obs-hour = [CFWS] 2DIGIT [CFWS]
obs-hour = [CFWS] 2DIGIT [CFWS]
obs-minute = [CFWS] 2DIGIT [CFWS]
obs-minute = [CFWS] 2DIGIT [CFWS]
obs-second = [CFWS] 2DIGIT [CFWS]
obs-second = [CFWS] 2DIGIT [CFWS]
obs-zone = "UT" / "GMT" / ; Universal Time
; North American UT
; offsets
"EST" / "EDT" / ; Eastern: - 5/ - 4
"CST" / "CDT" / ; Central: - 6/ - 5
"MST" / "MDT" / ; Mountain: - 7/ - 6
"PST" / "PDT" / ; Pacific: - 8/ - 7
;
obs-zone = "UT" / "GMT" / ; Universal Time
; North American UT
; offsets
"EST" / "EDT" / ; Eastern: - 5/ - 4
"CST" / "CDT" / ; Central: - 6/ - 5
"MST" / "MDT" / ; Mountain: - 7/ - 6
"PST" / "PDT" / ; Pacific: - 8/ - 7
;
%d65-73 / ; Military zones - "A"
%d75-90 / ; through "I" and "K"
%d97-105 / ; through "Z", both
%d107-122 ; upper and lower case
%d65-73 / ; Military zones - "A"
%d75-90 / ; through "I" and "K"
%d97-105 / ; through "Z", both
%d107-122 ; upper and lower case
Where a two or three digit year occurs in a date, the year is to be interpreted as follows: If a two digit year is encountered whose value is between 00 and 49, the year is interpreted by adding 2000, ending up with a value between 2000 and 2049. If a two digit year is encountered with a value between 50 and 99, or any three digit year is encountered, the year is interpreted by adding 1900.
如果日期中出现两位或三位数字的年份，则该年份应按如下方式解释：如果遇到值介于00和49之间的两位数字年份，则该年份应加上2000，以2000和2049之间的值结束。如果遇到值介于50和99之间的两位数年份，或遇到任何三位数年份，则该年份将通过添加1900来解释。
In the obsolete time zone, "UT" and "GMT" are indications of "Universal Time" and "Greenwich Mean Time", respectively, and are both semantically identical to "+0000".
在过时的时区中，“UT”和“GMT”分别表示“世界时”和“格林威治标准时间”，在语义上都与“+0000”相同。
The remaining three character zones are the US time zones. The first letter, "E", "C", "M", or "P" stands for "Eastern", "Central", "Mountain", and "Pacific". The second letter is either "S" for "Standard" time, or "D" for "Daylight Savings" (or summer) time. Their interpretations are as follows:
剩下的三个字符区是美国时区。第一个字母“E”、“C”、“M”或“P”代表“东部”、“中部”、“山脉”和“太平洋”。第二个字母是“S”表示“标准”时间，或“D”表示“夏令时”（或夏季）时间。他们的解释如下：
EDT is semantically equivalent to -0400 EST is semantically equivalent to -0500 CDT is semantically equivalent to -0500 CST is semantically equivalent to -0600 MDT is semantically equivalent to -0600 MST is semantically equivalent to -0700 PDT is semantically equivalent to -0700 PST is semantically equivalent to -0800
EDT在语义上等价于-0400 EST在语义上等价于-0500 CDT在语义上等价于-0500 CST在语义上等价于-0600 MDT在语义上等价于-0600 MST在语义上等价于-0700 PDT在语义上等价于-0700 PST在语义上等价于-0800
The 1 character military time zones were defined in a non-standard way in [RFC0822] and are therefore unpredictable in their meaning. The original definitions of the military zones "A" through "I" are equivalent to "+0100" through "+0900", respectively; "K", "L", and "M" are equivalent to "+1000", "+1100", and "+1200", respectively; "N" through "Y" are equivalent to "-0100" through "-1200". respectively; and "Z" is equivalent to "+0000". However, because of the error in [RFC0822], they SHOULD all be considered equivalent to "-0000" unless there is out-of-band information confirming their meaning.
[RFC0822]中以非标准方式定义了1个字符的军事时区，因此其含义不可预测。“A”至“I”军事区的原始定义分别相当于“+0100”至“+0900”；“K”、“L”和“M”分别相当于“+1000”、“+1100”和“+1200”；“N”到“Y”相当于“-0100”到“-1200”。分别地“Z”相当于“+0000”。但是，由于[RFC0822]中的错误，除非有带外信息确认其含义，否则应将其视为等同于“-0000”。
Other multi-character (usually between 3 and 5) alphabetic time zones have been used in Internet messages. Any such time zone whose meaning is not known SHOULD be considered equivalent to "-0000" unless there is out-of-band information confirming their meaning.
互联网信息中还使用了其他多字符（通常在3到5个字母之间）时区。除非有带外信息确认其含义，否则含义未知的任何此类时区应视为等同于“-0000”。
There are four primary differences in addressing. First, mailbox addresses were allowed to have a route portion before the addr-spec when enclosed in "<" and ">". The route is simply a comma-separated list of domain names, each preceded by "@", and the list terminated by a colon. Second, CFWS were allowed between the period-separated elements of local-part and domain (i.e., dot-atom was not used). In addition, local-part is allowed to contain quoted-string in addition to just atom. Third, mailbox-list and address-list were allowed to have "null" members. That is, there could be two or more commas in such a list with nothing in between them, or commas at the beginning or end of the list. Finally, US-ASCII control characters and quoted-pairs were allowed in domain literals and are added here.
称呼有四个主要区别。首先，邮箱地址被允许在addr规范之前有一个路由部分，当包含在“<”和“>”中时。路由只是一个逗号分隔的域名列表，每个名称前面都有“@”，列表以冒号结尾。其次，局部部分和域的周期分离元素之间允许CFW（即，不使用点原子）。此外，除了atom之外，本地部分还允许包含带引号的字符串。第三，邮箱列表和地址列表允许有“空”成员。也就是说，在这样一个列表中可能有两个或多个逗号，它们之间没有任何内容，或者在列表的开头或结尾有逗号。最后，允许在域文字中使用US-ASCII控制字符和引号对，并将其添加到此处。
obs-angle-addr = [CFWS] "<" obs-route addr-spec ">" [CFWS]
obs-angle-addr = [CFWS] "<" obs-route addr-spec ">" [CFWS]
obs-route = obs-domain-list ":"
obs路由=obs域列表“：”
obs-domain-list = *(CFWS / ",") "@" domain
*("," [CFWS] ["@" domain])
obs-domain-list = *(CFWS / ",") "@" domain
*("," [CFWS] ["@" domain])
obs-mbox-list = *([CFWS] ",") mailbox *("," [mailbox / CFWS])
obs-mbox-list = *([CFWS] ",") mailbox *("," [mailbox / CFWS])
obs-addr-list = *([CFWS] ",") address *("," [address / CFWS])
obs-addr-list = *([CFWS] ",") address *("," [address / CFWS])
obs-group-list = 1*([CFWS] ",") [CFWS]
obs-group-list = 1*([CFWS] ",") [CFWS]
obs-local-part = word *("." word)
obs本地部分=字*（“”字）
obs-domain = atom *("." atom)
obs域=原子*（“”原子）
obs-dtext = obs-NO-WS-CTL / quoted-pair
obs-dtext = obs-NO-WS-CTL / quoted-pair
When interpreting addresses, the route portion SHOULD be ignored.
在解释地址时，应该忽略路由部分。
Syntactically, the primary difference in the obsolete field syntax is that it allows multiple occurrences of any of the fields and they may occur in any order. Also, any amount of white space is allowed before the ":" at the end of the field name.
从语法上讲，过时字段语法的主要区别在于它允许任何字段多次出现，并且它们可以以任何顺序出现。此外，在字段名末尾的“：”之前允许有任意数量的空白。
obs-fields = *(obs-return /
obs-received /
obs-orig-date /
obs-from /
obs-sender /
obs-reply-to /
obs-to /
obs-cc /
obs-bcc /
obs-message-id /
obs-in-reply-to /
obs-references /
obs-subject /
obs-comments /
obs-keywords /
obs-resent-date /
obs-resent-from /
obs-resent-send /
obs-resent-rply /
obs-resent-to /
obs-resent-cc /
obs-resent-bcc /
obs-resent-mid /
obs-optional)
obs-fields = *(obs-return /
obs-received /
obs-orig-date /
obs-from /
obs-sender /
obs-reply-to /
obs-to /
obs-cc /
obs-bcc /
obs-message-id /
obs-in-reply-to /
obs-references /
obs-subject /
obs-comments /
obs-keywords /
obs-resent-date /
obs-resent-from /
obs-resent-send /
obs-resent-rply /
obs-resent-to /
obs-resent-cc /
obs-resent-bcc /
obs-resent-mid /
obs-optional)
Except for destination address fields (described in section 4.5.3), the interpretation of multiple occurrences of fields is unspecified. Also, the interpretation of trace fields and resent fields that do not occur in blocks prepended to the message is unspecified as well. Unless otherwise noted in the following sections, interpretation of other fields is identical to the interpretation of their non-obsolete counterparts in section 3.
除目的地址字段（如第4.5.3节所述）外，未指定字段多次出现的解释。此外，还未指定在消息前面的块中不出现的跟踪字段和重新发送字段的解释。除非在以下章节中另有说明，否则其他字段的解释与第3节中未过时字段的解释相同。
obs-orig-date = "Date" *WSP ":" date-time CRLF
obs-orig-date = "Date" *WSP ":" date-time CRLF
obs-from = "From" *WSP ":" mailbox-list CRLF
obs-from = "From" *WSP ":" mailbox-list CRLF
obs-sender = "Sender" *WSP ":" mailbox CRLF
obs-sender = "Sender" *WSP ":" mailbox CRLF
obs-reply-to = "Reply-To" *WSP ":" address-list CRLF
obs-reply-to = "Reply-To" *WSP ":" address-list CRLF
obs-to = "To" *WSP ":" address-list CRLF
obs-to = "To" *WSP ":" address-list CRLF
obs-cc = "Cc" *WSP ":" address-list CRLF
obs-cc = "Cc" *WSP ":" address-list CRLF
obs-bcc = "Bcc" *WSP ":"
(address-list / (*([CFWS] ",") [CFWS])) CRLF
obs-bcc = "Bcc" *WSP ":"
(address-list / (*([CFWS] ",") [CFWS])) CRLF
When multiple occurrences of destination address fields occur in a message, they SHOULD be treated as if the address list in the first occurrence of the field is combined with the address lists of the subsequent occurrences by adding a comma and concatenating.
当消息中多次出现目标地址字段时，应将其视为第一次出现的字段中的地址列表通过添加逗号和连接与后续出现的地址列表相结合。
The obsolete "In-Reply-To:" and "References:" fields differ from the current syntax in that they allow phrase (words or quoted strings) to appear. The obsolete forms of the left and right sides of msg-id allow interspersed CFWS, making them syntactically identical to local-part and domain, respectively.
过时的“回复：”和“引用：”字段与当前语法不同，它们允许出现短语（单词或带引号的字符串）。msg id左侧和右侧的过时形式允许散布CFW，使它们在语法上分别与本地部分和域相同。
obs-message-id = "Message-ID" *WSP ":" msg-id CRLF
obs-message-id = "Message-ID" *WSP ":" msg-id CRLF
obs-in-reply-to = "In-Reply-To" *WSP ":" *(phrase / msg-id) CRLF
obs-in-reply-to = "In-Reply-To" *WSP ":" *(phrase / msg-id) CRLF
obs-references = "References" *WSP ":" *(phrase / msg-id) CRLF
obs-references = "References" *WSP ":" *(phrase / msg-id) CRLF
obs-id-left = local-part
obs-id-left = local-part
obs-id-right = domain
obs-id-right = domain
For purposes of interpretation, the phrases in the "In-Reply-To:" and "References:" fields are ignored.
为了便于解释，“回复：”和“参考：”字段中的短语将被忽略。
Semantically, none of the optional CFWS in the local-part and the domain is part of the obs-id-left and obs-id-right, respectively.
从语义上讲，本地部分和域中的可选CFW都不是obs id left和obs id right的一部分。
obs-subject = "Subject" *WSP ":" unstructured CRLF
obs-subject = "Subject" *WSP ":" unstructured CRLF
obs-comments = "Comments" *WSP ":" unstructured CRLF
obs-comments = "Comments" *WSP ":" unstructured CRLF
obs-keywords = "Keywords" *WSP ":" obs-phrase-list CRLF
obs-keywords = "Keywords" *WSP ":" obs-phrase-list CRLF
The obsolete syntax adds a "Resent-Reply-To:" field, which consists of the field name, the optional comments and folding white space, the colon, and a comma separated list of addresses.
过时的语法添加了一个“Resent Reply To:”字段，该字段由字段名、可选注释和折叠空格、冒号以及逗号分隔的地址列表组成。
obs-resent-from = "Resent-From" *WSP ":" mailbox-list CRLF
obs-resent-from = "Resent-From" *WSP ":" mailbox-list CRLF
obs-resent-send = "Resent-Sender" *WSP ":" mailbox CRLF
obs-resent-send = "Resent-Sender" *WSP ":" mailbox CRLF
obs-resent-date = "Resent-Date" *WSP ":" date-time CRLF
obs-resent-date = "Resent-Date" *WSP ":" date-time CRLF
obs-resent-to = "Resent-To" *WSP ":" address-list CRLF
obs-resent-to = "Resent-To" *WSP ":" address-list CRLF
obs-resent-cc = "Resent-Cc" *WSP ":" address-list CRLF
obs-resent-cc = "Resent-Cc" *WSP ":" address-list CRLF
obs-resent-bcc = "Resent-Bcc" *WSP ":"
(address-list / (*([CFWS] ",") [CFWS])) CRLF
obs-resent-bcc = "Resent-Bcc" *WSP ":"
(address-list / (*([CFWS] ",") [CFWS])) CRLF
obs-resent-mid = "Resent-Message-ID" *WSP ":" msg-id CRLF
obs-resent-mid = "Resent-Message-ID" *WSP ":" msg-id CRLF
obs-resent-rply = "Resent-Reply-To" *WSP ":" address-list CRLF
obs-resent-rply = "Resent-Reply-To" *WSP ":" address-list CRLF
As with other resent fields, the "Resent-Reply-To:" field is to be treated as trace information only.
与其他重新发送字段一样，“重新发送回复：”字段仅作为跟踪信息处理。
The obs-return and obs-received are again given here as template definitions, just as return and received are in section 3. Their full syntax is given in [RFC5321].
obs返回和接收的obs在这里再次作为模板定义给出，正如第3节中的返回和接收一样。它们的完整语法在[RFC5321]中给出。
obs-return = "Return-Path" *WSP ":" path CRLF
obs-return = "Return-Path" *WSP ":" path CRLF
obs-received = "Received" *WSP ":" *received-token CRLF
obs-received = "Received" *WSP ":" *received-token CRLF
obs-optional = field-name *WSP ":" unstructured CRLF
obs-optional = field-name *WSP ":" unstructured CRLF
Care needs to be taken when displaying messages on a terminal or terminal emulator. Powerful terminals may act on escape sequences and other combinations of US-ASCII control characters with a variety of consequences. They can remap the keyboard or permit other modifications to the terminal that could lead to denial of service or even damaged data. They can trigger (sometimes programmable)
在终端或终端仿真器上显示消息时需要小心。功能强大的终端可能对转义序列和US-ASCII控制字符的其他组合起作用，并产生各种后果。他们可以重新映射键盘或允许对终端进行其他修改，从而导致拒绝服务甚至数据损坏。它们可以触发（有时可编程）
answerback messages that can allow a message to cause commands to be issued on the recipient's behalf. They can also affect the operation of terminal attached devices such as printers. Message viewers may wish to strip potentially dangerous terminal escape sequences from the message prior to display. However, other escape sequences appear in messages for useful purposes (cf. [ISO.2022.1994], [RFC2045], [RFC2046], [RFC2047], [RFC2049], [RFC4288], [RFC4289]) and therefore should not be stripped indiscriminately.
应答消息，允许消息代表收件人发出命令。它们还可能影响终端连接设备（如打印机）的操作。消息查看者可能希望在显示之前从消息中去除潜在危险的终端逃生序列。然而，出于有用的目的，其他转义序列出现在消息中（参见[ISO.2022.1994]、[RFC2045]、[RFC2046]、[RFC2047]、[RFC2049]、[RFC4288]、[RFC4289]），因此不应不加区别地剥离。
Transmission of non-text objects in messages raises additional security issues. These issues are discussed in [RFC2045], [RFC2046], [RFC2047], [RFC2049], [RFC4288], and [RFC4289].
在消息中传输非文本对象会引发其他安全问题。[RFC2045]、[RFC2046]、[RFC2047]、[RFC2049]、[RFC4288]和[RFC4289]中讨论了这些问题。
Many implementations use the "Bcc:" (blind carbon copy) field, described in section 3.6.3, to facilitate sending messages to recipients without revealing the addresses of one or more of the addressees to the other recipients. Mishandling this use of "Bcc:" may disclose confidential information that could eventually lead to security problems through knowledge of even the existence of a particular mail address. For example, if using the first method described in section 3.6.3, where the "Bcc:" line is removed from the message, blind recipients have no explicit indication that they have been sent a blind copy, except insofar as their address does not appear in the header section of a message. Because of this, one of the blind addressees could potentially send a reply to all of the shown recipients and accidentally reveal that the message went to the blind recipient. When the second method from section 3.6.3 is used, the blind recipient's address appears in the "Bcc:" field of a separate copy of the message. If the "Bcc:" field sent contains all of the blind addressees, all of the "Bcc:" recipients will be seen by each "Bcc:" recipient. Even if a separate message is sent to each "Bcc:" recipient with only the individual's address, implementations still need to be careful to process replies to the message as per section 3.6.3 so as not to accidentally reveal the blind recipient to other recipients.
许多实施方案使用第3.6.3节所述的“密件抄送：”（盲拷贝）字段，以便于向收件人发送消息，而无需向其他收件人透露一个或多个收件人的地址。错误地使用“密件抄送：”可能会泄露机密信息，即使知道某个特定邮件地址的存在，也可能最终导致安全问题。例如，如果使用第3.6.3节中描述的第一种方法，其中“密件抄送：”行从邮件中删除，则盲收件人没有明确指示他们已发送盲副本，除非他们的地址未出现在邮件的标题部分。因此，其中一个盲收件人可能会向所有显示的收件人发送回复，并意外地透露该邮件是发送给盲收件人的。当使用第3.6.3节中的第二种方法时，盲收件人的地址将显示在邮件单独副本的“密件抄送：”字段中。如果发送的“密件抄送：”字段包含所有盲收件人，则每个“密件抄送：”收件人将看到所有“密件抄送：”收件人。即使向每个“密件抄送：”收件人发送单独的邮件，且只提供个人地址，实施过程中仍需注意按照第3.6.3节处理对邮件的回复，以免意外地将盲收件人透露给其他收件人。
This document updates the registrations that appeared in [RFC4021] that referred to the definitions in [RFC2822]. IANA has updated the Permanent Message Header Field Repository with the following header fields, in accordance with the procedures set out in [RFC3864].
本文档更新了[RFC4021]中出现的涉及[RFC2822]中定义的注册。IANA已根据[RFC3864]中规定的程序，使用以下标题字段更新了永久邮件标题字段存储库。
Header field name: Date
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.1)
Header field name: Date
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.1)
Header field name: From
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.2)
Header field name: From
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.2)
Header field name: Sender
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.2)
Header field name: Sender
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.2)
Header field name: Reply-To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.2)
Header field name: Reply-To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.2)
Header field name: To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.3)
Header field name: To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.3)
Header field name: Cc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.3)
Header field name: Cc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.3)
Header field name: Bcc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.3)
Header field name: Bcc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.3)
Header field name: Message-ID
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.4)
Header field name: Message-ID
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.4)
Header field name: In-Reply-To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.4)
Header field name: In-Reply-To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.4)
Header field name: References
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.4)
Header field name: References
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.4)
Header field name: Subject
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.5)
Header field name: Subject
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.5)
Header field name: Comments
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.5)
Header field name: Comments
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.5)
Header field name: Keywords
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.5)
Header field name: Keywords
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.5)
Header field name: Resent-Date
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Date
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-From
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-From
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Sender
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Sender
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-To
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Cc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Cc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Bcc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Bcc
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Reply-To
Applicable protocol: Mail
Status: obsolete
Author/Change controller: IETF
Specification document(s): This document (section 4.5.6)
Header field name: Resent-Reply-To
Applicable protocol: Mail
Status: obsolete
Author/Change controller: IETF
Specification document(s): This document (section 4.5.6)
Header field name: Resent-Message-ID
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Resent-Message-ID
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.6)
Header field name: Return-Path
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.7)
Header field name: Return-Path
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.7)
Header field name: Received
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.7)
Related information: [RFC5321]
Header field name: Received
Applicable protocol: Mail
Status: standard
Author/Change controller: IETF
Specification document(s): This document (section 3.6.7)
Related information: [RFC5321]
This section presents a selection of messages. These are intended to assist in the implementation of this specification, but should not be taken as normative; that is to say, although the examples in this section were carefully reviewed, if there happens to be a conflict between these examples and the syntax described in sections 3 and 4 of this document, the syntax in those sections is to be taken as correct.
本节介绍一系列消息。这些文件旨在帮助实施本规范，但不应视为规范性文件；也就是说，尽管本节中的示例经过了仔细审查，但如果这些示例与本文件第3节和第4节中描述的语法之间存在冲突，则这些章节中的语法应视为正确。
In the text version of this document, messages in this section are
delimited between lines of "----". The "----" lines are not part of
the message itself.
In the text version of this document, messages in this section are
delimited between lines of "----". The "----" lines are not part of
the message itself.
Appendix A.1. Addressing Examples
附录A.1。举例说明
The following are examples of messages that might be sent between two individuals.
以下是两个人之间可能发送的消息示例。
Appendix A.1.1. A Message from One Person to Another with Simple Addressing
附录A.1.1。通过简单的地址从一个人发送给另一个人的信息
This could be called a canonical message. It has a single author, John Doe, a single recipient, Mary Smith, a subject, the date, a message identifier, and a textual message in the body.
这可以称为规范消息。它有一个作者，John Doe，一个接收者，Mary Smith，一个主题，一个日期，一个消息标识符，以及正文中的文本消息。
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
If John's secretary Michael actually sent the message, even though John was the author and replies to this message should go back to him, the sender field would be used:
如果John的秘书Michael确实发送了该邮件，即使John是该邮件的作者，对此邮件的回复应返回给他，发件人字段将被使用：
----
From: John Doe <jdoe@machine.example>
Sender: Michael Jones <mjones@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
----
From: John Doe <jdoe@machine.example>
Sender: Michael Jones <mjones@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
Appendix A.1.2. Different Types of Mailboxes
附录A.1.2。不同类型的邮箱
This message includes multiple addresses in the destination fields and also uses several different forms of addresses.
此消息在目标字段中包含多个地址，并且还使用几种不同形式的地址。
----
From: "Joe Q. Public" <john.q.public@example.com>
To: Mary Smith <mary@x.test>, jdoe@example.org, Who? <one@y.test>
Cc: <boss@nil.test>, "Giant; \"Big\" Box" <sysservices@example.net>
Date: Tue, 1 Jul 2003 10:52:37 +0200
Message-ID: <5678.21-Nov-1997@example.com>
----
From: "Joe Q. Public" <john.q.public@example.com>
To: Mary Smith <mary@x.test>, jdoe@example.org, Who? <one@y.test>
Cc: <boss@nil.test>, "Giant; \"Big\" Box" <sysservices@example.net>
Date: Tue, 1 Jul 2003 10:52:37 +0200
Message-ID: <5678.21-Nov-1997@example.com>
Hi everyone.
----
Hi everyone.
----
Note that the display names for Joe Q. Public and Giant; "Big" Box needed to be enclosed in double-quotes because the former contains the period and the latter contains both semicolon and double-quote characters (the double-quote characters appearing as quoted-pair constructs). Conversely, the display name for Who? could appear without them because the question mark is legal in an atom. Notice also that jdoe@example.org and boss@nil.test have no display names associated with them at all, and jdoe@example.org uses the simpler address form without the angle brackets.
请注意，Joe Q.Public和Giant的显示名称；“大”框需要用双引号括起来，因为前者包含句点，后者包含分号和双引号字符（双引号字符显示为引号对结构）。相反，谁的显示名称？因为问号在原子中是合法的。还要注意jdoe@example.org和boss@nil.test完全没有与之关联的显示名称，并且jdoe@example.org使用不带尖括号的更简单的地址形式。
Appendix A.1.3. Group Addresses
附录A.1.3。组地址
----
From: Pete <pete@silly.example>
To: A Group:Ed Jones <c@a.test>,joe@where.test,John <jdoe@one.test>;
Cc: Undisclosed recipients:;
Date: Thu, 13 Feb 1969 23:32:54 -0330
Message-ID: <testabcd.1234@silly.example>
----
From: Pete <pete@silly.example>
To: A Group:Ed Jones <c@a.test>,joe@where.test,John <jdoe@one.test>;
Cc: Undisclosed recipients:;
Date: Thu, 13 Feb 1969 23:32:54 -0330
Message-ID: <testabcd.1234@silly.example>
Testing.
----
Testing.
----
In this message, the "To:" field has a single group recipient named "A Group", which contains 3 addresses, and a "Cc:" field with an empty group recipient named Undisclosed recipients.
在此消息中，“收件人：”字段有一个名为“a组”的组收件人，其中包含3个地址，还有一个名为“未公开收件人”的空组收件人的“抄送：”字段。
Appendix A.2. Reply Messages
附录A.2。回复信息
The following is a series of three messages that make up a conversation thread between John and Mary. John first sends a message to Mary, Mary then replies to John's message, and then John replies to Mary's reply message.
以下是一系列三条消息，它们构成了John和Mary之间的对话线索。约翰先给玛丽发一条信息，玛丽再回复约翰的信息，然后约翰回复玛丽的回复信息。
Note especially the "Message-ID:", "References:", and "In-Reply-To:" fields in each message.
特别注意每条消息中的“消息ID:”、“引用：”、“回复：”字段。
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
When sending replies, the Subject field is often retained, though prepended with "Re: " as described in section 3.6.5.
发送回复时，主题字段通常会保留，尽管前面有“Re:”字样，如第3.6.5节所述。
----
From: Mary Smith <mary@example.net>
To: John Doe <jdoe@machine.example>
Reply-To: "Mary Smith: Personal Account" <smith@home.example>
Subject: Re: Saying Hello
Date: Fri, 21 Nov 1997 10:01:10 -0600
Message-ID: <3456@example.net>
In-Reply-To: <1234@local.machine.example>
References: <1234@local.machine.example>
----
From: Mary Smith <mary@example.net>
To: John Doe <jdoe@machine.example>
Reply-To: "Mary Smith: Personal Account" <smith@home.example>
Subject: Re: Saying Hello
Date: Fri, 21 Nov 1997 10:01:10 -0600
Message-ID: <3456@example.net>
In-Reply-To: <1234@local.machine.example>
References: <1234@local.machine.example>
This is a reply to your hello.
----
This is a reply to your hello.
----
Note the "Reply-To:" field in the above message. When John replies to Mary's message above, the reply should go to the address in the "Reply-To:" field instead of the address in the "From:" field.
注意上面消息中的“回复：”字段。当John回复上面Mary的邮件时，回复应该转到“回复到：”字段中的地址，而不是“发件人：”字段中的地址。
----
To: "Mary Smith: Personal Account" <smith@home.example>
From: John Doe <jdoe@machine.example>
Subject: Re: Saying Hello
Date: Fri, 21 Nov 1997 11:00:00 -0600
Message-ID: <abcd.1234@local.machine.test>
In-Reply-To: <3456@example.net>
References: <1234@local.machine.example> <3456@example.net>
----
To: "Mary Smith: Personal Account" <smith@home.example>
From: John Doe <jdoe@machine.example>
Subject: Re: Saying Hello
Date: Fri, 21 Nov 1997 11:00:00 -0600
Message-ID: <abcd.1234@local.machine.test>
In-Reply-To: <3456@example.net>
References: <1234@local.machine.example> <3456@example.net>
This is a reply to your reply.
----
This is a reply to your reply.
----
Appendix A.3. Resent Messages
附录A.3。重新发送消息
Start with the message that has been used as an example several times:
从多次用作示例的消息开始：
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
Say that Mary, upon receiving this message, wishes to send a copy of the message to Jane such that (a) the message would appear to have come straight from John; (b) if Jane replies to the message, the reply should go back to John; and (c) all of the original information, like the date the message was originally sent to Mary, the message identifier, and the original addressee, is preserved. In this case, resent fields are prepended to the message:
假设玛丽在收到这封信后，希望将这封信的副本发送给简，以便（a）这封信看起来是约翰直接发来的；（b） 如果Jane回复了邮件，回复应该返回给John；（c）保留所有原始信息，如消息最初发送给Mary的日期、消息标识符和原始收件人。在这种情况下，重新发送字段在消息前面：
----
Resent-From: Mary Smith <mary@example.net>
Resent-To: Jane Brown <j-brown@other.example>
Resent-Date: Mon, 24 Nov 1997 14:22:01 -0800
Resent-Message-ID: <78910@example.net>
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
----
Resent-From: Mary Smith <mary@example.net>
Resent-To: Jane Brown <j-brown@other.example>
Resent-Date: Mon, 24 Nov 1997 14:22:01 -0800
Resent-Message-ID: <78910@example.net>
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
If Jane, in turn, wished to resend this message to another person, she would prepend her own set of resent header fields to the above and send that. (Note that for brevity, trace fields are not shown.)
反过来，如果Jane希望将此消息重新发送给另一个人，她会将自己的一组“重新发送头”字段预先添加到上面并发送。（请注意，为简洁起见，未显示跟踪字段。）
Appendix A.4. Messages with Trace Fields
附录A.4。带有跟踪字段的消息
As messages are sent through the transport system as described in [RFC5321], trace fields are prepended to the message. The following is an example of what those trace fields might look like. Note that there is some folding white space in the first one since these lines can be long.
正如[RFC5321]中所述，当消息通过传输系统发送时，跟踪字段被预先添加到消息中。下面是这些跟踪字段的示例。请注意，第一行中有一些可折叠的空白，因为这些行可能很长。
----
Received: from x.y.test
by example.net
via TCP
with ESMTP
id ABC12345
for <mary@example.net>; 21 Nov 1997 10:05:43 -0600
Received: from node.example by x.y.test; 21 Nov 1997 10:01:22 -0600
From: John Doe <jdoe@node.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.node.example>
----
Received: from x.y.test
by example.net
via TCP
with ESMTP
id ABC12345
for <mary@example.net>; 21 Nov 1997 10:05:43 -0600
Received: from node.example by x.y.test; 21 Nov 1997 10:01:22 -0600
From: John Doe <jdoe@node.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.node.example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
Appendix A.5. White Space, Comments, and Other Oddities
附录A.5。空白、评论和其他奇怪之处
White space, including folding white space, and comments can be inserted between many of the tokens of fields. Taking the example from A.1.3, white space and comments can be inserted into all of the fields.
空白（包括折叠空白）和注释可以插入字段的许多标记之间。以A.1.3中的示例为例，可以在所有字段中插入空格和注释。
----
From: Pete(A nice \) chap) <pete(his account)@silly.test(his host)>
To:A Group(Some people)
:Chris Jones <c@(Chris's host.)public.example>,
joe@example.org,
John <jdoe@one.test> (my dear friend); (the end of the group)
Cc:(Empty list)(start)Hidden recipients :(nobody(that I know)) ;
Date: Thu,
13
Feb
1969
23:32
-0330 (Newfoundland Time)
Message-ID: <testabcd.1234@silly.test>
----
From: Pete(A nice \) chap) <pete(his account)@silly.test(his host)>
To:A Group(Some people)
:Chris Jones <c@(Chris's host.)public.example>,
joe@example.org,
John <jdoe@one.test> (my dear friend); (the end of the group)
Cc:(Empty list)(start)Hidden recipients :(nobody(that I know)) ;
Date: Thu,
13
Feb
1969
23:32
-0330 (Newfoundland Time)
Message-ID: <testabcd.1234@silly.test>
Testing.
----
Testing.
----
The above example is aesthetically displeasing, but perfectly legal. Note particularly (1) the comments in the "From:" field (including one that has a ")" character appearing as part of a quoted-pair); (2) the white space absent after the ":" in the "To:" field as well as the comment and folding white space after the group name, the special character (".") in the comment in Chris Jones's address, and the folding white space before and after "joe@example.org,"; (3) the multiple and nested comments in the "Cc:" field as well as the comment immediately following the ":" after "Cc"; (4) the folding white space (but no comments except at the end) and the missing seconds in the time of the date field; and (5) the white space before (but not within) the identifier in the "Message-ID:" field.
上述例子在美学上令人不快，但完全合法。特别注意（1）“发件人：”字段中的注释（包括带有“）”字符的注释，作为引用对的一部分出现）；（2） “收件人：”字段中“：”后面的空白，以及组名后面的注释和折叠空白，Chris Jones地址中注释中的特殊字符（“.”），以及前后的折叠空白joe@example.org,"; （3） “Cc:”字段中的多个嵌套注释以及紧跟在“：”之后的注释；（4） 折叠空白（但除结尾处外无注释）和日期字段时间中缺失的秒数；以及（5）“消息ID:”字段中标识符之前（但不在其内）的空白。
Appendix A.6. Obsoleted Forms
附录A.6。过时的表格
The following are examples of obsolete (that is, the "MUST NOT generate") syntactic elements described in section 4 of this document.
以下是本文件第4节中描述的过时（即“不得生成”）语法元素的示例。
Appendix A.6.1. Obsolete Addressing
附录A.6.1。过时寻址
Note in the example below the lack of quotes around Joe Q. Public, the route that appears in the address for Mary Smith, the two commas that appear in the "To:" field, and the spaces that appear around the "." in the jdoe address.
请注意，在下面的示例中，Joe Q.Public、Mary Smith地址中出现的路由、To:“字段中出现的两个逗号以及jdoe地址中“.”周围出现的空格缺少引号。
----
From: Joe Q. Public <john.q.public@example.com>
To: Mary Smith <@node.test:mary@example.net>, , jdoe@test . example
Date: Tue, 1 Jul 2003 10:52:37 +0200
Message-ID: <5678.21-Nov-1997@example.com>
----
From: Joe Q. Public <john.q.public@example.com>
To: Mary Smith <@node.test:mary@example.net>, , jdoe@test . example
Date: Tue, 1 Jul 2003 10:52:37 +0200
Message-ID: <5678.21-Nov-1997@example.com>
Hi everyone.
----
Hi everyone.
----
Appendix A.6.2. Obsolete Dates
附录A.6.2。过时日期
The following message uses an obsolete date format, including a non-numeric time zone and a two digit year. Note that although the day-of-week is missing, that is not specific to the obsolete syntax; it is optional in the current syntax as well.
以下消息使用过时的日期格式，包括非数字时区和两位数年份。请注意，虽然缺少星期几，但这不是过时语法所特有的；在当前语法中也是可选的。
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: 21 Nov 97 09:55:06 GMT
Message-ID: <1234@local.machine.example>
----
From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: 21 Nov 97 09:55:06 GMT
Message-ID: <1234@local.machine.example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
Appendix A.6.3. Obsolete White Space and Comments
附录A.6.3。过时的空白和注释
White space and comments can appear between many more elements than in the current syntax. Also, folding lines that are made up entirely of white space are legal.
与当前语法相比，空格和注释可以出现在更多的元素之间。此外，完全由空白组成的折叠线也是合法的。
----
From : John Doe <jdoe@machine(comment). example>
To : Mary Smith
__
<mary@example.net>
Subject : Saying Hello
Date : Fri, 21 Nov 1997 09(comment): 55 : 06 -0600
Message-ID : <1234 @ local(blah) .machine .example>
----
From : John Doe <jdoe@machine(comment). example>
To : Mary Smith
__
<mary@example.net>
Subject : Saying Hello
Date : Fri, 21 Nov 1997 09(comment): 55 : 06 -0600
Message-ID : <1234 @ local(blah) .machine .example>
This is a message just to say hello.
So, "Hello".
----
This is a message just to say hello.
So, "Hello".
----
Note especially the second line of the "To:" field. It starts with
two space characters. (Note that "__" represent blank spaces.)
Therefore, it is considered part of the folding, as described in
section 4.2. Also, the comments and white space throughout
addresses, dates, and message identifiers are all part of the
obsolete syntax.
Note especially the second line of the "To:" field. It starts with
two space characters. (Note that "__" represent blank spaces.)
Therefore, it is considered part of the folding, as described in
section 4.2. Also, the comments and white space throughout
addresses, dates, and message identifiers are all part of the
obsolete syntax.
This appendix contains a list of changes that have been made in the Internet Message Format from earlier specifications, specifically [RFC0822], [RFC1123], and [RFC2822]. Items marked with an asterisk (*) below are items which appear in section 4 of this document and therefore can no longer be generated.
本附录包含先前规范（具体为[RFC0822]、[RFC1123]和[RFC2822]）中对互联网消息格式所做更改的列表。以下标有星号（*）的项目为本文件第4节中出现的项目，因此无法再生成。
The following are the changes made from [RFC0822] and [RFC1123] to [RFC2822] that remain in this document:
以下是从[RFC0822]和[RFC1123]到[RFC2822]所做的更改，这些更改保留在本文件中：
1. Period allowed in obsolete form of phrase. 2. ABNF moved out of document, now in [RFC5234]. 3. Four or more digits allowed for year. 4. Header field ordering (and lack thereof) made explicit. 5. Encrypted header field removed. 6. Specifically allow and give meaning to "-0000" time zone. 7. Folding white space is not allowed between every token. 8. Requirement for destinations removed. 9. Forwarding and resending redefined. 10. Extension header fields no longer specifically called out. 11. ASCII 0 (null) removed.* 12. Folding continuation lines cannot contain only white space.* 13. Free insertion of comments not allowed in date.* 14. Non-numeric time zones not allowed.* 15. Two digit years not allowed.* 16. Three digit years interpreted, but not allowed for generation.* 17. Routes in addresses not allowed.* 18. CFWS within local-parts and domains not allowed.* 19. Empty members of address lists not allowed.* 20. Folding white space between field name and colon not allowed.* 21. Comments between field name and colon not allowed. 22. Tightened syntax of in-reply-to and references.* 23. CFWS within msg-id not allowed.* 24. Tightened semantics of resent fields as informational only. 25. Resent-Reply-To not allowed.* 26. No multiple occurrences of fields (except resent and received).* 27. Free CR and LF not allowed.* 28. Line length limits specified. 29. Bcc more clearly specified.
1. 以短语的过时形式允许的句号。2.ABNF从文档中移出，现在位于[RFC5234]。3.年允许四位或更多数字。4.明确了标题字段的顺序（以及缺少顺序）。5.已删除加密的标头字段。6.明确允许并赋予“-0000”时区含义。7.每个令牌之间不允许折叠空白。8.删除目的地的要求。9重新定义转发和重新发送。10扩展标题字段不再专门调用。11ASCII 0（空）已删除。*12。折叠续行不能仅包含空格。*13。日期中不允许自由插入注释。*14。不允许非数字时区。*15。不允许使用两位数年份。*16。已解释三位数年份，但不允许生成。*17。地址中不允许路由。*18。不允许本地部件和域内的CFW。*19。地址列表中不允许有空成员。*20。不允许在字段名和冒号之间折叠空格。*21。不允许在字段名和冒号之间添加注释。22在回复和参考资料时的紧缩语法。*23。不允许消息id内的CFW。*24。将resent字段的语义收紧为仅供参考。25不允许重新答复。*26。没有多次出现的字段（重新发送和接收除外）。*27。不允许使用免费CR和LF。*28。指定的行长度限制。29密件抄送更为明确。
The following are changes from [RFC2822]. 1. Assorted typographical/grammatical errors fixed and clarifications made. 2. Changed "standard" to "document" or "specification" throughout. 3. Made distinction between "header field" and "header section". 4. Removed NO-WS-CTL from ctext, qtext, dtext, and unstructured.* 5. Moved discussion of specials to the "Atom" section. Moved text to "Overall message syntax" section. 6. Simplified CFWS syntax. 7. Fixed unstructured syntax. 8. Changed date and time syntax to deal with white space in obsolete date syntax. 9. Removed quoted-pair from domain literals and message identifiers.* 10. Clarified that other specifications limit domain syntax. 11. Simplified "Bcc:" and "Resent-Bcc:" syntax. 12. Allowed optional-field to appear within trace information. 13. Removed no-fold-quote from msg-id. Clarified syntax limitations. 14. Generalized "Received:" syntax to fix bugs and move definition out of this document. 15. Simplified obs-qp. Fixed and simplified obs-utext (which now only appears in the obsolete syntax). Removed obs-text and obs-char, adding obs-body. 16. Fixed obsolete date syntax to allow for more (or less) comments and white space. 17. Fixed all obsolete list syntax (obs-domain-list, obs-mbox-list, obs-addr-list, obs-phrase-list, and the newly added obs-group-list). 18. Fixed obs-reply-to syntax. 19. Fixed obs-bcc and obs-resent-bcc to allow empty lists. 20. Removed obs-path.
以下是对[RFC2822]的更改。1.修复了各种印刷/语法错误，并进行了澄清。2.将“标准”改为“文件”或“规范”。3.对“标题字段”和“标题部分”进行了区分。4.已从ctext、qtext、dtext和非结构化中删除NO-WS-CTL。*5。将特价商品的讨论移至“原子”部分。将文本移动到“总体消息语法”部分。6.简化的CFWS语法。7.修复了非结构化语法。8.更改了日期和时间语法，以处理过时日期语法中的空白。9已从域文字和消息标识符中删除引号对。*10。阐明了其他规范限制域语法。11简化的“密件抄送：”和“重新发送密件抄送：”语法。12允许在跟踪信息中显示可选字段。13删除了msg-id中的无折叠引号。澄清了语法限制。14通用的“Received:”语法，用于修复错误并将定义移出本文档。15简化obs qp。固定和简化的obs utext（现在仅以过时的语法显示）。删除了obs文本和obs字符，添加了obs正文。16修复了过时的日期语法，允许更多（或更少）注释和空白。17修复了所有过时的列表语法（obs域列表、obs mbox列表、obs地址列表、obs短语列表和新添加的obs组列表）。18修复了obs回复语法。19修复了obs密件抄送和obs重新发送密件抄送允许空列表的问题。20已删除obs路径。
Many people contributed to this document. They included folks who participated in the Detailed Revision and Update of Messaging Standards (DRUMS) Working Group of the Internet Engineering Task Force (IETF), the chair of DRUMS, the Area Directors of the IETF, and people who simply sent their comments in via email. The editor is deeply indebted to them all and thanks them sincerely. The below list includes everyone who sent email concerning both this document and [RFC2822]. Hopefully, everyone who contributed is named here:
许多人对这份文件作出了贡献。他们包括参与互联网工程任务组（IETF）消息传递标准（TRUMS）工作组详细修订和更新的人员、TRUMS主席、IETF区域主管，以及通过电子邮件发送评论的人员。编辑非常感激他们，并衷心感谢他们。以下列表包括发送有关本文件和[RFC2822]的电子邮件的所有人。希望所有贡献者的名字都在这里：
+--------------------+----------------------+---------------------+
| Matti Aarnio | Tanaka Akira | Russ Allbery |
| Eric Allman | Harald Alvestrand | Ran Atkinson |
| Jos Backus | Bruce Balden | Dave Barr |
+--------------------+----------------------+---------------------+
| Matti Aarnio | Tanaka Akira | Russ Allbery |
| Eric Allman | Harald Alvestrand | Ran Atkinson |
| Jos Backus | Bruce Balden | Dave Barr |
| Alan Barrett | John Beck | J Robert von Behren |
| Jos den Bekker | D J Bernstein | James Berriman |
| Oliver Block | Norbert Bollow | Raj Bose |
| Antony Bowesman | Scott Bradner | Randy Bush |
| Tom Byrer | Bruce Campbell | Larry Campbell |
| W J Carpenter | Michael Chapman | Richard Clayton |
| Maurizio Codogno | Jim Conklin | R Kelley Cook |
| Nathan Coulter | Steve Coya | Mark Crispin |
| Dave Crocker | Matt Curtin | Michael D'Errico |
| Cyrus Daboo | Michael D Dean | Jutta Degener |
| Mark Delany | Steve Dorner | Harold A Driscoll |
| Michael Elkins | Frank Ellerman | Robert Elz |
| Johnny Eriksson | Erik E Fair | Roger Fajman |
| Patrik Faltstrom | Claus Andre Faerber | Barry Finkel |
| Erik Forsberg | Chuck Foster | Paul Fox |
| Klaus M Frank | Ned Freed | Jochen Friedrich |
| Randall C Gellens | Sukvinder Singh Gill | Tim Goodwin |
| Philip Guenther | Arnt Gulbrandsen | Eric A Hall |
| Tony Hansen | John Hawkinson | Philip Hazel |
| Kai Henningsen | Robert Herriot | Paul Hethmon |
| Jim Hill | Alfred Hoenes | Paul E Hoffman |
| Steve Hole | Kari Hurtta | Marco S Hyman |
| Ofer Inbar | Olle Jarnefors | Kevin Johnson |
| Sudish Joseph | Maynard Kang | Prabhat Keni |
| John C Klensin | Graham Klyne | Brad Knowles |
| Shuhei Kobayashi | Peter Koch | Dan Kohn |
| Christian Kuhtz | Anand Kumria | Steen Larsen |
| Eliot Lear | Barry Leiba | Jay Levitt |
| Bruce Lilly | Lars-Johan Liman | Charles Lindsey |
| Pete Loshin | Simon Lyall | Bill Manning |
| John Martin | Mark Martinec | Larry Masinter |
| Denis McKeon | William P McQuillan | Alexey Melnikov |
| Perry E Metzger | Steven Miller | S Moonesamy |
| Keith Moore | John Gardiner Myers | Chris Newman |
| John W Noerenberg | Eric Norman | Mike O'Dell |
| Larry Osterman | Paul Overell | Jacob Palme |
| Michael A Patton | Uzi Paz | Michael A Quinlan |
| Robert Rapplean | Eric S Raymond | Sam Roberts |
| Hugh Sasse | Bart Schaefer | Tom Scola |
| Wolfgang Segmuller | Nick Shelness | John Stanley |
| Einar Stefferud | Jeff Stephenson | Bernard Stern |
| Peter Sylvester | Mark Symons | Eric Thomas |
| Lee Thompson | Karel De Vriendt | Matthew Wall |
| Rolf Weber | Brent B Welch | Dan Wing |
| Jack De Winter | Gregory J Woodhouse | Greg A Woods |
| Kazu Yamamoto | Alain Zahm | Jamie Zawinski |
| Timothy S Zurcher | | |
+--------------------+----------------------+---------------------+
| Alan Barrett | John Beck | J Robert von Behren |
| Jos den Bekker | D J Bernstein | James Berriman |
| Oliver Block | Norbert Bollow | Raj Bose |
| Antony Bowesman | Scott Bradner | Randy Bush |
| Tom Byrer | Bruce Campbell | Larry Campbell |
| W J Carpenter | Michael Chapman | Richard Clayton |
| Maurizio Codogno | Jim Conklin | R Kelley Cook |
| Nathan Coulter | Steve Coya | Mark Crispin |
| Dave Crocker | Matt Curtin | Michael D'Errico |
| Cyrus Daboo | Michael D Dean | Jutta Degener |
| Mark Delany | Steve Dorner | Harold A Driscoll |
| Michael Elkins | Frank Ellerman | Robert Elz |
| Johnny Eriksson | Erik E Fair | Roger Fajman |
| Patrik Faltstrom | Claus Andre Faerber | Barry Finkel |
| Erik Forsberg | Chuck Foster | Paul Fox |
| Klaus M Frank | Ned Freed | Jochen Friedrich |
| Randall C Gellens | Sukvinder Singh Gill | Tim Goodwin |
| Philip Guenther | Arnt Gulbrandsen | Eric A Hall |
| Tony Hansen | John Hawkinson | Philip Hazel |
| Kai Henningsen | Robert Herriot | Paul Hethmon |
| Jim Hill | Alfred Hoenes | Paul E Hoffman |
| Steve Hole | Kari Hurtta | Marco S Hyman |
| Ofer Inbar | Olle Jarnefors | Kevin Johnson |
| Sudish Joseph | Maynard Kang | Prabhat Keni |
| John C Klensin | Graham Klyne | Brad Knowles |
| Shuhei Kobayashi | Peter Koch | Dan Kohn |
| Christian Kuhtz | Anand Kumria | Steen Larsen |
| Eliot Lear | Barry Leiba | Jay Levitt |
| Bruce Lilly | Lars-Johan Liman | Charles Lindsey |
| Pete Loshin | Simon Lyall | Bill Manning |
| John Martin | Mark Martinec | Larry Masinter |
| Denis McKeon | William P McQuillan | Alexey Melnikov |
| Perry E Metzger | Steven Miller | S Moonesamy |
| Keith Moore | John Gardiner Myers | Chris Newman |
| John W Noerenberg | Eric Norman | Mike O'Dell |
| Larry Osterman | Paul Overell | Jacob Palme |
| Michael A Patton | Uzi Paz | Michael A Quinlan |
| Robert Rapplean | Eric S Raymond | Sam Roberts |
| Hugh Sasse | Bart Schaefer | Tom Scola |
| Wolfgang Segmuller | Nick Shelness | John Stanley |
| Einar Stefferud | Jeff Stephenson | Bernard Stern |
| Peter Sylvester | Mark Symons | Eric Thomas |
| Lee Thompson | Karel De Vriendt | Matthew Wall |
| Rolf Weber | Brent B Welch | Dan Wing |
| Jack De Winter | Gregory J Woodhouse | Greg A Woods |
| Kazu Yamamoto | Alain Zahm | Jamie Zawinski |
| Timothy S Zurcher | | |
+--------------------+----------------------+---------------------+
[ANSI.X3-4.1986] American National Standards Institute, "Coded Character Set - 7-bit American Standard Code for Information Interchange", ANSI X3.4, 1986.
[ANSI.X3-4.1986]美国国家标准协会，“编码字符集-信息交换用7位美国标准代码”，ANSI X3.41986。
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987.
[RFC1034]Mockapetris，P.，“域名-概念和设施”，STD 13，RFC 1034，1987年11月。
[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987.
[RFC1035]Mockapetris，P.，“域名-实现和规范”，STD 13，RFC 1035，1987年11月。
[RFC1123] Braden, R., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, October 1989.
[RFC1123]Braden，R.，“互联网主机的要求-应用和支持”，STD 3，RFC 1123，1989年10月。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5234]Crocker，D.和P.Overell，“语法规范的扩充BNF:ABNF”，STD 68，RFC 5234，2008年1月。
[RFC0822] Crocker, D., "Standard for the format of ARPA Internet text messages", STD 11, RFC 822, August 1982.
[RFC0822]Crocker，D.，“ARPA互联网文本信息格式标准”，STD 11，RFC 822，1982年8月。
[RFC1305] Mills, D., "Network Time Protocol (Version 3) Specification, Implementation", RFC 1305, March 1992.
[RFC1305]Mills，D.，“网络时间协议（版本3）规范，实施”，RFC1305，1992年3月。
[ISO.2022.1994] International Organization for Standardization, "Information technology - Character code structure and extension techniques", ISO Standard 2022, 1994.
[ISO.2022.1994]国际标准化组织，“信息技术-字符代码结构和扩展技术”，ISO标准20221994。
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996.
[RFC2045]Freed，N.和N.Borenstein，“多用途Internet邮件扩展（MIME）第一部分：Internet邮件正文格式”，RFC 20451996年11月。
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, November 1996.
[RFC2046]Freed，N.和N.Borenstein，“多用途Internet邮件扩展（MIME）第二部分：媒体类型”，RFC 20461996年11月。
[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text", RFC 2047, November 1996.
[RFC2047]Moore，K.，“MIME（多用途互联网邮件扩展）第三部分：非ASCII文本的消息头扩展”，RFC 2047，1996年11月。
[RFC2049] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples", RFC 2049, November 1996.
[RFC2049]Freed，N.和N.Borenstein，“多用途Internet邮件扩展（MIME）第五部分：一致性标准和示例”，RFC 2049，1996年11月。
[RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[RFC2822]Resnick，P.，“互联网信息格式”，RFC 2822，2001年4月。
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, September 2004.
[RFC3864]Klyne，G.，Nottingham，M.和J.Mogul，“消息头字段的注册程序”，BCP 90，RFC 3864，2004年9月。
[RFC4021] Klyne, G. and J. Palme, "Registration of Mail and MIME Header Fields", RFC 4021, March 2005.
[RFC4021]Klyne，G.和J.Palme，“邮件和MIME头字段的注册”，RFC4021，2005年3月。
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC4288]Freed，N.和J.Klensin，“介质类型规范和注册程序”，BCP 13，RFC 4288，2005年12月。
[RFC4289] Freed, N. and J. Klensin, "Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures", BCP 13, RFC 4289, December 2005.
[RFC4289]Freed，N.和J.Klensin，“多用途互联网邮件扩展（MIME）第四部分：注册程序”，BCP 13，RFC 4289，2005年12月。
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, October 2008.
[RFC5321]Klensin，J.，“简单邮件传输协议”，RFC 53212008年10月。
Author's Address
作者地址
Peter W. Resnick (editor) Qualcomm Incorporated 5775 Morehouse Drive San Diego, CA 92121-1714 US
Peter W.Resnick（编辑）美国加利福尼亚州圣地亚哥Morehouse大道5775号高通公司，邮编92121-1714
Phone: +1 858 651 4478
EMail: presnick@qualcomm.com
URI: http://www.qualcomm.com/~presnick/
Phone: +1 858 651 4478
EMail: presnick@qualcomm.com
URI: http://www.qualcomm.com/~presnick/
Full Copyright Statement
完整版权声明
Copyright (C) The IETF Trust (2008).
版权所有（C）IETF信托基金（2008年）。
This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights.
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