Network Working Group C. Newman
Request for Comments: 4468 Sun Microsystems
Updates: 3463 May 2006
Category: Standards Track
Network Working Group C. Newman
Request for Comments: 4468 Sun Microsystems
Updates: 3463 May 2006
Category: Standards Track
Message Submission BURL Extension
消息提交BURL扩展
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。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2006).
版权所有（C）互联网协会（2006年）。
Abstract
摘要
The submission profile of Simple Mail Transfer Protocol (SMTP) provides a standard way for an email client to submit a complete message for delivery. This specification extends the submission profile by adding a new BURL command that can be used to fetch submission data from an Internet Message Access Protocol (IMAP) server. This permits a mail client to inject content from an IMAP server into the SMTP infrastructure without downloading it to the client and uploading it back to the server.
简单邮件传输协议（SMTP）的提交配置文件为电子邮件客户端提交完整邮件以进行传递提供了标准方式。此规范通过添加新的BURL命令扩展提交配置文件，该命令可用于从Internet消息访问协议（IMAP）服务器获取提交数据。这允许邮件客户端将IMAP服务器中的内容注入SMTP基础结构，而无需将其下载到客户端并将其上载回服务器。
Table of Contents
目录
1. Introduction ....................................................2
2. Conventions Used in This Document ...............................2
3. BURL Submission Extension .......................................3
3.1. SMTP Submission Extension Registration .....................3
3.2. BURL Transaction ...........................................3
3.3. The BURL IMAP Options ......................................4
3.4. Examples ...................................................5
3.5. Formal Syntax ..............................................6
4. 8-Bit and Binary ................................................7
5. Updates to RFC 3463 .............................................7
6. Response Codes ..................................................7
7. IANA Considerations .............................................9
8. Security Considerations .........................................9
9. References .....................................................11
9.1. Normative References ......................................11
9.2. Informative References ....................................12
Appendix A. Acknowledgements .....................................13
1. Introduction ....................................................2
2. Conventions Used in This Document ...............................2
3. BURL Submission Extension .......................................3
3.1. SMTP Submission Extension Registration .....................3
3.2. BURL Transaction ...........................................3
3.3. The BURL IMAP Options ......................................4
3.4. Examples ...................................................5
3.5. Formal Syntax ..............................................6
4. 8-Bit and Binary ................................................7
5. Updates to RFC 3463 .............................................7
6. Response Codes ..................................................7
7. IANA Considerations .............................................9
8. Security Considerations .........................................9
9. References .....................................................11
9.1. Normative References ......................................11
9.2. Informative References ....................................12
Appendix A. Acknowledgements .....................................13
This specification defines an extension to the standard Message Submission [RFC4409] protocol to permit data to be fetched from an IMAP server at message submission time. This MAY be used in conjunction with the CHUNKING [RFC3030] mechanism so that chunks of the message can come from an external IMAP server. This provides the ability to forward an email message without first downloading it to the client.
本规范定义了标准消息提交[RFC4409]协议的扩展，以允许在消息提交时从IMAP服务器获取数据。这可以与分块[RFC3030]机制结合使用，以便消息的分块可以来自外部IMAP服务器。这提供了转发电子邮件的能力，而无需先将其下载到客户端。
The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as defined in "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].
本文件中的关键词“必须”、“不得”、“应该”、“不应该”和“可能”应按照“RFC中用于指示需求水平的关键词”中的定义进行解释[RFC2119]。
The formal syntax uses the Augmented Backus-Naur Form (ABNF) [RFC4234] notation including the core rules defined in Appendix B of RFC 4234.
形式语法使用扩展的巴科斯诺尔形式（ABNF）[RFC4234]符号，包括RFC 4234附录B中定义的核心规则。
This section defines the BURL submission extension.
本节定义BURL提交扩展。
1. The name of this submission extension is "BURL". This extends the Message Submission protocol on port 587 and MUST NOT be advertised by a regular SMTP [RFC2821] server on port 25 that acts as a relay for incoming mail from other SMTP relays.
1. 此提交扩展名为“BURL”。这扩展了端口587上的邮件提交协议，并且端口25上的常规SMTP[RFC2821]服务器不得播发该协议，该服务器充当从其他SMTP中继接收邮件的中继。
2. The EHLO keyword value associated with the extension is "BURL".
2. 与扩展关联的EHLO关键字值为“BURL”。
3. The BURL EHLO keyword will have zero or more arguments. The only argument defined at this time is the "imap" argument, which MUST be present in order to use IMAP URLs with BURL. Clients MUST ignore other arguments after the BURL EHLO keyword unless they are defined by a subsequent IETF standards track specification. The arguments that appear after the BURL EHLO keyword may change subsequent to the use of SMTP AUTH [RFC2554], so a server that advertises BURL with no arguments prior to authentication indicates that BURL is supported but authentication is required to use it.
3. BURL EHLO关键字将具有零个或多个参数。此时定义的唯一参数是“imap”参数，必须存在该参数才能将imap URL与BURL一起使用。客户端必须忽略BURL EHLO关键字后面的其他参数，除非它们由后续的IETF标准跟踪规范定义。在使用SMTP AUTH[RFC2554]之后，出现在BURL EHLO关键字之后的参数可能会更改，因此在身份验证之前播发BURL且没有参数的服务器表示支持BURL，但使用它需要身份验证。
4. This extension adds the BURL SMTP verb. This verb is used as a replacement for the DATA command and is only permitted during a mail transaction after at least one successful RCPT TO.
4. 此扩展添加了BURL SMTP谓词。此谓词用作DATA命令的替换，仅在至少一次成功的RCPT发送到后的邮件事务期间才允许使用。
A simple BURL transaction will consist of MAIL FROM, one or more RCPT TO headers, and a BURL command with the "LAST" tag. The BURL command will include an IMAP URL pointing to a fully formed message ready for injection into the SMTP infrastructure. If PIPELINING [RFC2920] is advertised, the client MAY send the entire transaction in one round trip. If no valid RCPT TO address is supplied, the BURL command will simply fail, and no resolution of the BURL URL argument will be performed. If at least one valid RCPT TO address is supplied, then the BURL URL argument will be resolved before the server responds to the command.
一个简单的BURL事务将由邮件发件人、一个或多个RCPT TO头和一个带有“LAST”标记的BURL命令组成。BURL命令将包括一个IMAP URL，该URL指向一个完整格式的消息，该消息可随时注入SMTP基础结构。如果公布了管道[RFC2920]，则客户端可以在一次往返中发送整个事务。如果没有提供有效的RCPT TO address，则BURL命令将失败，并且不会执行BURL URL参数的解析。如果至少提供了一个有效的RCPT-TO-address，则在服务器响应命令之前，将解析BURL URL参数。
A more sophisticated BURL transaction MAY occur when the server also advertises CHUNKING [RFC3030]. In this case, the BURL and BDAT commands may be interleaved until one of them terminates the transaction with the "LAST" argument. If PIPELINING [RFC2920] is also advertised, then the client may pipeline the entire transaction in one round-trip. However, it MUST wait for the results of the "LAST" BDAT or BURL command prior to initiating a new transaction.
当服务器同时播发分块[RFC3030]时，可能会发生更复杂的BURL事务。在这种情况下，BURL和BDAT命令可以交错，直到其中一个命令使用“LAST”参数终止事务。如果还公布了管道[RFC2920]，则客户机可以在一次往返中管道化整个事务。但是，在启动新事务之前，它必须等待“LAST”BDAT或BURL命令的结果。
The BURL command directs the server to fetch the data object to which the URL refers and include it in the message. If the URL fetch fails, the server will fail the entire transaction.
BURL命令指示服务器获取URL引用的数据对象，并将其包含在消息中。如果URL获取失败，服务器将使整个事务失败。
When "imap" is present in the space-separated list of arguments following the BURL EHLO keyword, it indicates that the BURL command supports the URLAUTH [RFC4467] extended form of IMAP URLs [RFC2192] and that the submit server is configured with the necessary credentials to resolve "urlauth=submit+" IMAP URLs for the submit server's domain.
当BURL EHLO关键字后面以空格分隔的参数列表中出现“imap”时，表示BURL命令支持URLAUTH[RFC4467]扩展形式的imap URL[RFC2192]，并且提交服务器配置了必要的凭据，以解析提交服务器域的“URLAUTH=submit+”imap URL。
Subsequent to a successful SMTP AUTH command, the submission server MAY indicate a prearranged trust relationship with a specific IMAP server by including a BURL EHLO keyword argument of the form "imap://imap.example.com". In this case, the submission server will permit a regular IMAP URL referring to messages or parts of messages on imap.example.com that the user who authenticated to the submit server can access. Note that this form does not imply that the submit server supports URLAUTH URLs; the submit server must advertise both "imap" and "imap://imap.example.com" to indicate support for both extended and non-extended URL forms.
成功执行SMTP AUTH命令后，提交服务器可能会通过包含以下形式的BURL EHLO关键字参数来指示与特定IMAP服务器的预先安排的信任关系“imap://imap.example.com". 在这种情况下，提交服务器将允许常规IMAP URL引用IMAP.example.com上的消息或部分消息，通过提交服务器身份验证的用户可以访问这些消息。请注意，此表单并不意味着提交服务器支持URLAUTH URL；提交服务器必须同时播发“imap”和imap://imap.example.com“表示对扩展URL表单和非扩展URL表单的支持。
When the submit server connects to the IMAP server, it acts as an IMAP client and thus is subject to both the mandatory-to-implement IMAP capabilities in Section 6.1.1 of RFC 3501, and the security considerations in Section 11 of RFC 3501. Specifically, this requires that the submit server implement a configuration that uses STARTTLS followed by SASL PLAIN [SASL-PLAIN] to authenticate to the IMAP server.
当提交服务器连接到IMAP服务器时，它充当IMAP客户端，因此受RFC 3501第6.1.1节中强制实施IMAP功能和RFC 3501第11节中安全注意事项的约束。具体地说，这要求提交服务器实现一种配置，该配置使用STARTTLS后跟SASL-PLAIN[SASL-PLAIN]向IMAP服务器进行身份验证。
When the submit server resolves a URLAUTH IMAP URL, it uses submit server credentials when authenticating to the IMAP server. The authentication identity and password used for submit credentials MUST be configurable. The string "submit" is suggested as a default value for the authentication identity, with no default for the password. Typically, the authorization identity is empty in this case; thus the IMAP server will derive the authorization identity from the authentication identity. If the IMAP URL uses the "submit+" access identifier prefix, the submit server MUST refuse the BURL command unless the userid in the URL's <access> token matches the submit client's authorization identity.
当提交服务器解析URLAUTH IMAP URL时，它在向IMAP服务器进行身份验证时使用提交服务器凭据。用于提交凭据的身份验证标识和密码必须是可配置的。建议将字符串“submit”作为身份验证标识的默认值，密码没有默认值。通常，在这种情况下，授权标识为空；因此，IMAP服务器将从身份验证标识派生授权标识。如果IMAP URL使用“submit+”访问标识符前缀，则提交服务器必须拒绝BURL命令，除非URL的<access>令牌中的用户ID与提交客户端的授权标识匹配。
When the submit server resolves a regular IMAP URL, it uses the submit client's authorization identity when authenticating to the IMAP server. If both the submit client and the submit server's embedded IMAP client use SASL PLAIN (or the equivalent), the submit
当提交服务器解析常规IMAP URL时，它在向IMAP服务器进行身份验证时使用提交客户端的授权标识。如果submit客户端和submit服务器的嵌入式IMAP客户端都使用SASL PLAIN（或同等版本），则submit
server SHOULD forward the client's credentials if and only if the submit server knows that the IMAP server is in the same administrative domain. If the submit server supports SASL mechanisms other than PLAIN, it MUST implement a configuration in which the submit server's embedded IMAP client uses STARTTLS and SASL PLAIN with the submit server's authentication identity and password (for the respective IMAP server) and the submit client's authorization identity.
当且仅当提交服务器知道IMAP服务器位于同一管理域中时，服务器才应转发客户端的凭据。如果提交服务器支持SASL机制而不是普通机制，则必须实现一种配置，其中提交服务器的嵌入式IMAP客户端使用STARTTLS和SASL PLAIN以及提交服务器的身份验证标识和密码（对于相应的IMAP服务器）和提交客户端的授权标识。
In examples, "C:" and "S:" indicate lines sent by the client and server, respectively. If a single "C:" or "S:" label applies to multiple lines, then the line breaks between those lines are for editorial clarity only and are not part of the actual protocol exchange.
在示例中，“C:”和“S:”分别表示客户端和服务器发送的行。如果单个“C:”或“S:”标签适用于多行，则这些行之间的换行符仅用于编辑清晰性，不属于实际协议交换的一部分。
Two successful submissions (without and with pipelining) follow:
以下是两份成功提交的文件（无管道和有管道）：
<SSL/TLS encryption layer negotiated>
C: EHLO potter.example.com
S: 250-owlry.example.com
S: 250-8BITMIME
S: 250-BURL imap
S: 250-AUTH PLAIN
S: 250-DSN
S: 250 ENHANCEDSTATUSCODES
C: AUTH PLAIN aGFycnkAaGFycnkAYWNjaW8=
S: 235 2.7.0 PLAIN authentication successful.
C: MAIL FROM:<harry@gryffindor.example.com>
S: 250 2.5.0 Address Ok.
C: RCPT TO:<ron@gryffindor.example.com>
S: 250 2.1.5 ron@gryffindor.example.com OK.
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:91354a473744909de610943775f92038 LAST
S: 250 2.5.0 Ok.
<SSL/TLS encryption layer negotiated>
C: EHLO potter.example.com
S: 250-owlry.example.com
S: 250-8BITMIME
S: 250-BURL imap
S: 250-AUTH PLAIN
S: 250-DSN
S: 250 ENHANCEDSTATUSCODES
C: AUTH PLAIN aGFycnkAaGFycnkAYWNjaW8=
S: 235 2.7.0 PLAIN authentication successful.
C: MAIL FROM:<harry@gryffindor.example.com>
S: 250 2.5.0 Address Ok.
C: RCPT TO:<ron@gryffindor.example.com>
S: 250 2.1.5 ron@gryffindor.example.com OK.
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:91354a473744909de610943775f92038 LAST
S: 250 2.5.0 Ok.
<SSL/TLS encryption layer negotiated>
C: EHLO potter.example.com
S: 250-owlry.example.com
S: 250-8BITMIME
S: 250-PIPELINING
S: 250-BURL imap
S: 250-AUTH PLAIN
S: 250-DSN
S: 250 ENHANCEDSTATUSCODES
C: AUTH PLAIN aGFycnkAaGFycnkAYWNjaW8=
<SSL/TLS encryption layer negotiated>
C: EHLO potter.example.com
S: 250-owlry.example.com
S: 250-8BITMIME
S: 250-PIPELINING
S: 250-BURL imap
S: 250-AUTH PLAIN
S: 250-DSN
S: 250 ENHANCEDSTATUSCODES
C: AUTH PLAIN aGFycnkAaGFycnkAYWNjaW8=
C: MAIL FROM:<harry@gryffindor.example.com>
C: RCPT TO:<ron@gryffindor.example.com>
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:91354a473744909de610943775f92038 LAST
S: 235 2.7.0 PLAIN authentication successful.
S: 250 2.5.0 Address Ok.
S: 250 2.1.5 ron@gryffindor.example.com OK.
S: 250 2.5.0 Ok.
C: MAIL FROM:<harry@gryffindor.example.com>
C: RCPT TO:<ron@gryffindor.example.com>
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:91354a473744909de610943775f92038 LAST
S: 235 2.7.0 PLAIN authentication successful.
S: 250 2.5.0 Address Ok.
S: 250 2.1.5 ron@gryffindor.example.com OK.
S: 250 2.5.0 Ok.
Note that PIPELINING of the AUTH command is only permitted if the selected mechanism can be completed in one round trip, a client initial response is provided, and no SASL security layer is negotiated. This is possible for PLAIN and EXTERNAL, but not for most other SASL mechanisms.
请注意，仅当所选机制可以在一次往返中完成、提供了客户端初始响应且未协商SASL安全层时，才允许AUTH命令的管道化。这对于普通的和外部的SASL机制是可能的，但对于大多数其他SASL机制是不可能的。
Some examples of failure cases:
故障案例的一些示例：
C: MAIL FROM:<harry@gryffindor.example.com>
C: RCPT TO:<malfoy@slitherin.example.com>
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:91354a473744909de610943775f92038 LAST
S: 250 2.5.0 Address Ok.
S: 550 5.7.1 Relaying not allowed: malfoy@slitherin.example.com
S: 554 5.5.0 No recipients have been specified.
C: MAIL FROM:<harry@gryffindor.example.com>
C: RCPT TO:<malfoy@slitherin.example.com>
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:91354a473744909de610943775f92038 LAST
S: 250 2.5.0 Address Ok.
S: 550 5.7.1 Relaying not allowed: malfoy@slitherin.example.com
S: 554 5.5.0 No recipients have been specified.
C: MAIL FROM:<harry@gryffindor.example.com>
C: RCPT TO:<ron@gryffindor.example.com>
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:71354a473744909de610943775f92038 LAST
S: 250 2.5.0 Address Ok.
S: 250 2.1.5 ron@gryffindor.example.com OK.
S: 554 5.7.0 IMAP URL authorization failed
C: MAIL FROM:<harry@gryffindor.example.com>
C: RCPT TO:<ron@gryffindor.example.com>
C: BURL imap://harry@gryffindor.example.com/outbox
;uidvalidity=1078863300/;uid=25;urlauth=submit+harry
:internal:71354a473744909de610943775f92038 LAST
S: 250 2.5.0 Address Ok.
S: 250 2.1.5 ron@gryffindor.example.com OK.
S: 554 5.7.0 IMAP URL authorization failed
The following syntax specification inherits ABNF [RFC4234] and Uniform Resource Identifiers [RFC3986].
以下语法规范继承ABNF[RFC4234]和统一资源标识符[RFC3986]。
burl-param = "imap" / ("imap://" authority)
; parameter to BURL EHLO keyword
burl-param = "imap" / ("imap://" authority)
; parameter to BURL EHLO keyword
burl-cmd = "BURL" SP absolute-URI [SP end-marker] CRLF
burl cmd=“burl”SP绝对URI[SP结束标记]CRLF
end-marker = "LAST"
end-marker = "LAST"
A submit server that advertises BURL MUST also advertise 8BITMIME [RFC1652] and perform the down conversion described in that specification on the resulting complete message if 8-bit data is received with the BURL command and passed to a 7-bit server. If the URL argument to BURL refers to binary data, then the submit server MAY refuse the command or down convert as described in Binary SMTP [RFC3030].
如果使用BURL命令接收8位数据并将其传递给7位服务器，则播发BURL的提交服务器还必须播发8BITMIME[RFC1652]，并对生成的完整消息执行该规范中所述的下转换。如果BURL的URL参数引用二进制数据，则提交服务器可能会拒绝该命令或按二进制SMTP[RFC3030]中的说明进行下变频。
The Submit server MAY refuse to accept a BURL command or combination of BURL and BDAT commands that result in un-encoded 8-bit data in mail or MIME [RFC2045] headers. Alternatively, the server MAY accept such data and down convert to MIME header encoding [RFC2047].
提交服务器可能拒绝接受导致邮件或MIME[RFC2045]头中未编码8位数据的BURL命令或BURL和BDAT命令的组合。或者，服务器可以接受此类数据并向下转换为MIME报头编码[RFC2047]。
SMTP or Submit servers that advertise ENHANCEDSTATUSCODES [RFC2034] use enhanced status codes defined in RFC 3463 [RFC3463]. The BURL extension introduces new error cases that that RFC did not consider. The following additional enhanced status codes are defined by this specification:
播发增强状态代码[RFC2034]的SMTP或提交服务器使用RFC 3463[RFC3463]中定义的增强状态代码。BURL扩展引入了RFC没有考虑的新的错误案例。本规范定义了以下额外的增强状态代码：
X.6.6 Message content not available
X.6.6 消息内容不可用
The message content could not be fetched from a remote system. This may be useful as a permanent or persistent temporary notification.
无法从远程系统获取邮件内容。作为永久或持久的临时通知，这可能很有用。
X.7.8 Trust relationship required
X.7.8 需要信任关系
The submission server requires a configured trust relationship with a third-party server in order to access the message content.
提交服务器需要配置与第三方服务器的信任关系才能访问邮件内容。
This section includes example response codes to the BURL command. Other text may be used with the same response codes. This list is not exhaustive, and BURL clients MUST tolerate any valid SMTP response code. Most of these examples include the appropriate enhanced status code [RFC3463].
本节包括BURL命令的响应代码示例。其他文本可与相同的响应代码一起使用。此列表并非详尽无遗，BURL客户端必须容忍任何有效的SMTP响应代码。大多数示例包括适当的增强状态代码[RFC3463]。
554 5.5.0 No recipients have been specified
554 5.5.0未指定收件人
This response code occurs when BURL is used (for example, with PIPELINING) and all RCPT TOs failed.
当使用BURL（例如，与管道连接）且所有RCPT TOs失败时，会出现此响应代码。
503 5.5.0 Valid RCPT TO required before BURL
503 5.5.0爆破前要求的有效RCPT
This response code is an alternative to the previous one when BURL is used (for example, with PIPELINING) and all RCPT TOs failed.
当使用BURL（例如，管道）且所有RCPT TOs失败时，此响应代码是前一个响应代码的替代代码。
554 5.6.3 Conversion required but not supported
554 5.6.3需要转换，但不支持
This response code occurs when the URL points to binary data and the implementation does not support down conversion to base64. This can also be used if the URL points to message data with 8-bit content in headers and the server does not down convert such content.
当URL指向二进制数据且实现不支持向下转换为base64时，会出现此响应代码。如果URL指向标题中包含8位内容的消息数据，并且服务器未向下转换此类内容，则也可以使用此选项。
554 5.3.4 Message too big for system
554 5.3.4消息对系统来说太大
The message (subsequent to URL resolution) is larger than the per-message size limit for this server.
邮件（在URL解析之后）大于此服务器的每封邮件大小限制。
554 5.7.8 URL resolution requires trust relationship
554 5.7.8 URL解析需要信任关系
The submit server does not have a trust relationship with the IMAP server specified in the URL argument to BURL.
提交服务器与BURL的URL参数中指定的IMAP服务器没有信任关系。
552 5.2.2 Mailbox full
552 5.2.2邮箱已满
The recipient is local, the submit server supports direct delivery, and the recipient has exceeded his quota and any grace period for delivery attempts.
收件人是本地的，提交服务器支持直接传递，并且收件人已超过其配额和任何传递尝试的宽限期。
554 5.6.6 IMAP URL resolution failed
554 5.6.6 IMAP URL解析失败
The IMAP URLFETCH command returned an error or no data.
IMAP URLFETCH命令返回错误或没有数据。
250 2.5.0 Waiting for additional BURL or BDAT commands
250 2.5.0等待其他BURL或BDAT命令
A BURL command without the "LAST" modifier was sent. The URL for this BURL command was successfully resolved, but the content will not necessarily be committed to persistent storage until the rest of the message content is collected. For example, a Unix server may have written the content to a queue file buffer, but may not yet have performed an fsync() operation. If the server loses power, the content can still be lost.
已发送不带“LAST”修饰符的BURL命令。已成功解析此BURL命令的URL，但在收集其余消息内容之前，内容不一定会提交到持久存储。例如，Unix服务器可能已将内容写入队列文件缓冲区，但可能尚未执行fsync（）操作。如果服务器断电，内容仍可能丢失。
451 4.4.1 IMAP server unavailable
451 4.4.1 IMAP服务器不可用
The connection to the IMAP server to resolve the URL failed.
连接到IMAP服务器以解析URL失败。
250 2.5.0 Ok.
250 2.5.0正常。
The URL was successfully resolved, and the complete message data has been committed to persistent storage.
URL已成功解析，完整的邮件数据已提交到永久性存储。
250 2.6.4 MIME header conversion with loss performed
250 2.6.4执行丢失的MIME报头转换
The URL pointed to message data that included mail or MIME headers with 8-bit data. This data was converted to MIME header encoding [RFC2047], but the submit server may not have correctly guessed the unlabeled character set.
URL指向包含8位数据的邮件或MIME头的邮件数据。此数据已转换为MIME标头编码[RFC2047]，但提交服务器可能没有正确猜测未标记的字符集。
The "BURL" SMTP extension as described in Section 3 has been registered. This registration has been marked for use by message submission [RFC4409] only in the registry.
已注册第3节所述的“BURL”SMTP扩展名。此注册已标记为仅在注册表中由消息提交[RFC4409]使用。
Modern SMTP submission servers often include content-based security and denial-of-service defense mechanisms such as virus filtering, size limits, server-generated signatures, spam filtering, etc. Implementations of BURL should fetch the URL content prior to application of such content-based mechanisms in order to preserve their function.
现代SMTP提交服务器通常包括基于内容的安全和拒绝服务防御机制，如病毒过滤、大小限制、服务器生成的签名、垃圾邮件过滤等。BURL的实现应在应用此类基于内容的机制之前获取URL内容，以保留其功能。
Clients that generate unsolicited bulk email or email with viruses could use this mechanism to compensate for a slow link between the client and submit server. In particular, this mechanism would make it feasible for a programmable cell phone or other device on a slow link to become a significant source of unsolicited bulk email and/or viruses. This makes it more important for submit server vendors implementing BURL to have auditing and/or defenses against such denial-of-service attacks including mandatory authentication, logging that associates unique client identifiers with mail transactions, limits on reuse of the same IMAP URL, rate limits, recipient count limits, and content filters.
生成未经请求的批量电子邮件或带有病毒的电子邮件的客户端可以使用此机制来补偿客户端和提交服务器之间的慢速链接。特别是，这种机制将使慢速链路上的可编程手机或其他设备成为未经请求的批量电子邮件和/或病毒的重要来源。这使得实现BURL的提交服务器供应商对此类拒绝服务攻击进行审计和/或防御变得更加重要，包括强制身份验证、将唯一客户端标识符与邮件事务关联的日志记录、对重复使用相同IMAP URL的限制、速率限制、收件人计数限制、，和内容过滤器。
Transfer of the URLAUTH [RFC4467] form of IMAP URLs in the clear can expose the authorization token to network eavesdroppers. Implementations that support such URLs can address this issue by using a strong confidentiality protection mechanism. For example, the SMTP STARTTLS [RFC3207] and the IMAP STARTTLS [RFC3501] extensions, in combination with a configuration setting that requires their use with such IMAP URLs, would address this concern.
在clear中传输URLAUTH[RFC4467]形式的IMAP URL会将授权令牌暴露给网络窃听者。支持此类URL的实现可以通过使用强大的机密性保护机制来解决此问题。例如，SMTP STARTTLS[RFC3207]和IMAP STARTTLS[RFC3501]扩展，以及需要与此类IMAP URL一起使用的配置设置，可以解决此问题。
Use of a prearranged trust relationship between a submit server and a specific IMAP server introduces security considerations. A compromise of the submit server should not automatically compromise all accounts on the IMAP server, so trust relationships involving super-user proxy credentials are strongly discouraged. A system that requires the submit server to authenticate to the IMAP server with submit credentials and subsequently requires a URLAUTH URL to fetch any content addresses this concern. A trusted third party model for proxy credentials (such as that provided by Kerberos 5 [RFC4120]) would also suffice.
在提交服务器和特定IMAP服务器之间使用预先安排的信任关系会引入安全注意事项。提交服务器的泄露不应自动泄露IMAP服务器上的所有帐户，因此强烈反对涉及超级用户代理凭据的信任关系。要求提交服务器使用提交凭据向IMAP服务器进行身份验证，然后要求URLAUTH URL获取任何内容的系统解决了此问题。代理凭证的可信第三方模型（如Kerberos 5[RFC4120]提供的模型）也足够了。
When a client uses SMTP STARTTLS to send a BURL command that references non-public information, there is a user expectation that the entire message content will be treated confidentially. To address this expectation, the message submission server SHOULD use STARTTLS or a mechanism providing equivalent data confidentiality when fetching the content referenced by that URL.
当客户端使用SMTP STARTTLS发送引用非公开信息的BURL命令时，用户期望整个消息内容都会被保密处理。为了满足这一期望，消息提交服务器应该使用STARTTLS或在获取该URL引用的内容时提供等效数据机密性的机制。
A legitimate user of a submit server may try to compromise other accounts on the server by providing an IMAP URLAUTH URL that points to a server under that user's control that is designed to undermine the security of the submit server. For this reason, the IMAP client code that the submit server uses must be robust with respect to arbitrary input sizes (including large IMAP literals) and arbitrary delays from the IMAP server. Requiring a prearranged trust relationship between a submit server and the IMAP server also addresses this concern.
提交服务器的合法用户可能会试图通过提供指向该用户控制下的服务器的IMAP URLAUTH URL来破坏提交服务器的安全性，从而危害服务器上的其他帐户。因此，提交服务器使用的IMAP客户端代码对于任意输入大小（包括较大的IMAP文本）和来自IMAP服务器的任意延迟必须是健壮的。提交服务器和IMAP服务器之间需要预先安排的信任关系也解决了这个问题。
An authorized user of the submit server could set up a fraudulent IMAP server and pass a URL for that server to the submit server. The submit server might then contact the fraudulent IMAP server to authenticate with submit credentials and fetch content. There are several ways to mitigate this potential attack. A submit server that only uses submit credentials with a fixed set of trusted IMAP servers will not be vulnerable to exposure of those credentials. A submit server can treat the IMAP server as untrusted and include defenses for buffer overflows, denial-of-service slowdowns, and other potential attacks. Finally, because authentication is required to use BURL, it is possible to keep a secure audit trail and use that to detect and punish the offending party.
提交服务器的授权用户可以设置欺诈性IMAP服务器，并将该服务器的URL传递给提交服务器。然后，提交服务器可能会联系欺诈性IMAP服务器，以使用提交凭据进行身份验证并获取内容。有几种方法可以减轻这种潜在的攻击。仅将提交凭据与一组固定的受信任IMAP服务器一起使用的提交服务器不易暴露这些凭据。提交服务器可以将IMAP服务器视为不受信任的服务器，并包括对缓冲区溢出、拒绝服务减速和其他潜在攻击的防御。最后，因为使用BURL需要身份验证，所以可以保留一个安全的审计跟踪，并使用它来检测和惩罚违规方。
[RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D. Crocker, "SMTP Service Extension for 8bit-MIMEtransport", RFC 1652, July 1994.
[RFC1652]Klensin，J.，Freed，N.，Rose，M.，Stefferud，E.，和D.Crocker，“8bit MIMEtransport的SMTP服务扩展”，RFC 16521994年7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。
[RFC2192] Newman, C., "IMAP URL Scheme", RFC 2192, September 1997.
[RFC2192]纽曼，C.，“IMAP URL方案”，RFC21921997年9月。
[RFC2554] Myers, J., "SMTP Service Extension for Authentication", RFC 2554, March 1999.
[RFC2554]迈尔斯，J.，“用于身份验证的SMTP服务扩展”，RFC2554，1999年3月。
[RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001.
[RFC2821]Klensin，J.，“简单邮件传输协议”，RFC 28212001年4月。
[RFC3207] Hoffman, P., "SMTP Service Extension for Secure SMTP over Transport Layer Security", RFC 3207, February 2002.
[RFC3207]Hoffman，P.，“传输层安全SMTP的SMTP服务扩展”，RFC3207，2002年2月。
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1", RFC 3501, March 2003.
[RFC3501]Crispin，M.，“互联网消息访问协议-版本4rev1”，RFC 35012003年3月。
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005.
[RFC3986]Berners Lee，T.，Fielding，R.，和L.Masinter，“统一资源标识符（URI）：通用语法”，STD 66，RFC 3986，2005年1月。
[RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005.
[RFC4234]Crocker，D.和P.Overell，“语法规范的扩充BNF:ABNF”，RFC 4234，2005年10月。
[RFC4409] Gellens, R. and J. Klensin, "Message Submission for Mail", RFC 4409, April 2006.
[RFC4409]Gellens，R.和J.Klensin，“邮件邮件提交”，RFC 4409，2006年4月。
[RFC4467] Crispin, M., "Internet Message Access Protocol (IMAP) - URLAUTH Extension", RFC 4467, May 2006.
[RFC4467]Crispin，M.，“互联网消息访问协议（IMAP）-URLAUTH扩展”，RFC 4467，2006年5月。
[RFC2034] Freed, N., "SMTP Service Extension for Returning Enhanced Error Codes", RFC 2034, October 1996.
[RFC2034]Freed，N.，“用于返回增强错误代码的SMTP服务扩展”，RFC 20341996年10月。
[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。
[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。
[RFC2920] Freed, N., "SMTP Service Extension for Command Pipelining", STD 60, RFC 2920, September 2000.
2000年9月，SMTP扩展名为[C260，RFC]的命令被释放。
[RFC3030] Vaudreuil, G., "SMTP Service Extensions for Transmission of Large and Binary MIME Messages", RFC 3030, December 2000.
[RFC3030]Vaudreuil，G.“用于传输大型和二进制MIME消息的SMTP服务扩展”，RFC 3030，2000年12月。
[RFC3463] Vaudreuil, G., "Enhanced Mail System Status Codes", RFC 3463, January 2003.
[RFC3463]Vaudreuil，G.，“增强邮件系统状态代码”，RFC 3463，2003年1月。
[RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The Kerberos Network Authentication Service (V5)", RFC 4120, July 2005.
[RFC4120]Neuman，C.，Yu，T.，Hartman，S.，和K.Raeburn，“Kerberos网络身份验证服务（V5）”，RFC41202005年7月。
[SASL-PLAIN] Zeilenga, K., "The Plain SASL Mechanism", Work in Progress, March 2005.
[SASL-PLAIN]Zeilenga，K.，“平原SASL机制”，正在进行的工作，2005年3月。
This document is a product of the lemonade WG. Many thanks are due to all the participants of that working group for their input. Mark Crispin was instrumental in the conception of this mechanism. Thanks to Randall Gellens, Alexey Melnikov, Sam Hartman, Ned Freed, Dave Cridland, Peter Coates, and Mark Crispin for review comments on the document. Thanks to the RFC Editor for correcting the author's grammar mistakes. Thanks to Ted Hardie, Randall Gellens, Mark Crispin, Pete Resnick, and Greg Vaudreuil for extremely interesting debates comparing this proposal and alternatives. Thanks to the lemonade WG chairs Eric Burger and Glenn Parsons for concluding the debate at the correct time and making sure this document got completed.
本文件是柠檬水工作组的产品。非常感谢该工作组所有与会者的投入。马克·克里斯平在这一机制的构想中发挥了重要作用。感谢Randall Gellens、Alexey Melnikov、Sam Hartman、Ned Freed、Dave Cridland、Peter Coates和Mark Crispin对该文件的评论。感谢RFC编辑纠正了作者的语法错误。感谢Ted Hardie、Randall Gellens、Mark Crispin、Pete Resnick和Greg Vaudreuil对该提案和备选方案进行了非常有趣的辩论。感谢柠檬水工作组主席埃里克·伯格（Eric Burger）和格伦·帕森斯（Glenn Parsons）在正确的时间结束辩论并确保完成本文件。
Author's Address
作者地址
Chris Newman Sun Microsystems 3401 Centrelake Dr., Suite 410 Ontario, CA 91761 US
Chris Newman Sun Microsystems 3401 Centrelake博士，美国加利福尼亚州安大略省410号套房，邮编：91761
EMail: chris.newman@sun.com
EMail: chris.newman@sun.com
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确认
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