我正在编写一个对发送到邮箱的电子邮件有反应的应用程序。它通过IMAP检索电子邮件。它将部署到我不控制邮件服务器配置的许多系统中。
我想使用IMAP标志来指示已处理的消息。系统标志是否得到足够广泛的支持，可以在我的应用程序中合理地依赖它们？用户定义的标志是否得到足够广泛的支持？
（如果答案是“哈哈，没有机会”，那么我将改用文件夹。）
谢谢
-本
我正在编写一个对发送到邮箱的电子邮件有反应的应用程序。它通过IMAP检索电子邮件。它将部署到我不控制邮件服务器配置的许多系统中。
我想使用IMAP标志来指示已处理的消息。系统标志是否得到足够广泛的支持，可以在我的应用程序中合理地依赖它们？用户定义的标志是否得到足够广泛的支持？
（如果答案是“哈哈，没有机会”，那么我将改用文件夹。）
谢谢
-本
Answers:
看一下示例IMAP服务器会话的集合。本质上，只要您看到PERMANENTFLAGS包含\*，服务器就会支持用户定义的标志。
要添加到该列表，以下是Gimap（Google Mail IMAP）会话的摘录：
* OK Gimap ready for requests from 192.0.2.1 5if380490pzk.17
a login username password
* CAPABILITY IMAP4rev1 UNSELECT LITERAL+ IDLE NAMESPACE QUOTA ID XLIST CHILDREN X-GM-EXT-1 UIDPLUS COMPRESS=DEFLATE
a OK username@gmail.com authenticated (Success)
b select inbox
* FLAGS (\Answered \Flagged \Draft \Deleted \Seen)
* OK [PERMANENTFLAGS (\Answered \Flagged \Draft \Deleted \Seen \*)]
* OK [UIDVALIDITY 2]
* 1089 EXISTS
* 0 RECENT
* OK [UIDNEXT 2371]
b OK [READ-WRITE] inbox selected. (Success)
c logout
* BYE LOGOUT Requested
c OK 73 good day (Success)
同样，来自Exchange 2007的会话：
* OK Microsoft Exchange Server 2007 IMAP4 service ready
00000000 CAPABILITY
* CAPABILITY IMAP4 IMAP4rev1 AUTH=NTLM AUTH=GSSAPI IDLE NAMESPACE LITERAL+
00000000 OK CAPABILITY completed.
[...]
00000003 SELECT INBOX
* 1 EXISTS
* 0 RECENT
* FLAGS (\Seen \Answered \Flagged \Deleted \Draft $MDNSent)
* OK [PERMANENTFLAGS (\Seen \Answered \Flagged \Deleted \Draft $MDNSent)] Permanent flags
* OK [UIDVALIDITY 472] UIDVALIDITY value
* OK [UIDNEXT 7] The next unique identifier value
00000003 OK [READ-WRITE] SELECT completed.
我无法从Exchange 2010中找到会话。
所以它不是通用的-Exchange是著名的弃权者-但它肯定比没有更普遍。
IMAP协议的主要文档是RFC3501。第2.3.2节介绍了每个 IMAP实现必须使用的标准标志。
系统标志是否得到足够广泛的支持，可以在我的应用程序中合理地依赖它们？
实际上，RFC3501描述了通用系统标志。
用户定义的标志是否得到足够广泛的支持？
关于用户定义标志的主题，没有任何RFC，只有proposal。
RFC 3501 IMAPv4 March 2003
2.3.2. Flags Message Attribute
A list of zero or more named tokens associated with the message. A
flag is set by its addition to this list, and is cleared by its
removal. There are two types of flags in IMAP4rev1. A flag of
either type can be permanent or session-only.
A system flag is a flag name that is pre-defined in this
specification. All system flags begin with "\". Certain system
flags (\Deleted and \Seen) have special semantics described
elsewhere. The currently-defined system flags are:
\Seen
Message has been read
\Answered
Message has been answered
\Flagged
Message is "flagged" for urgent/special attention
\Deleted
Message is "deleted" for removal by later EXPUNGE
\Draft
Message has not completed composition (marked as a draft).
\Recent
Message is "recently" arrived in this mailbox. This session
is the first session to have been notified about this
message; if the session is read-write, subsequent sessions
will not see \Recent set for this message. This flag can not
be altered by the client.
If it is not possible to determine whether or not this
session is the first session to be notified about a message,
then that message SHOULD be considered recent.
If multiple connections have the same mailbox selected
simultaneously, it is undefined which of these connections
will see newly-arrived messages with \Recent set and which
will see it without \Recent set.
A keyword is defined by the server implementation. Keywords do not
begin with "\". Servers MAY permit the client to define new keywords
in the mailbox (see the description of the PERMANENTFLAGS response
code for more information).
A flag can be permanent or session-only on a per-flag basis.
Permanent flags are those which the client can add or remove from the
message flags permanently; that is, concurrent and subsequent
sessions will see any change in permanent flags. Changes to session
flags are valid only in that session.
Note: The \Recent system flag is a special case of a
session flag. \Recent can not be used as an argument in a
STORE or APPEND command, and thus can not be changed at
all.
* OK [PERMANENTFLAGS (\Seen \Answered \Flagged \Deleted \Draft $MDNSent)] Permanent flags