Quoting Timo Sirainen <tss@iki.fi>:
On Mon, 2012-11-05 at 12:43 -0700, Michael M Slusarz wrote:
My argument is much simpler: it is blatantly breaking the RFC. From RFC 5162 [3.2]:
The VANISHED UID FETCH modifier instructs the server to report those messages from the UID set parameter that have been expunged and whose associated mod-sequence is larger than the specified mod-sequence. **That is, the client requests to be informed of messages from the specified set that were expunged since the specifiedmod-sequence.** (emphasis added)
If you are including UIDs in the FETCH return that have NOT been expunged since the given mod-sequence, that directly contradicts this language. The clear intent of VANISHED UID FETCH is to provide the list of messages that existed in the mailbox at mod-sequence and no longer exist in the mailbox as of the current HIGHESTMODSEQ.
That would require infinitely storing the modseq of when each message was expunged. Not very nice. Also the RFC talks a lot about this situation. The SELECT command has two optional parameters to optimize it.
The RFC *does* indicate that a server implementation could, strictly
speaking, be considered in compliance without remembering modsequences
for all expunged messages, but it does explicitly discourage such
implementations. From RFC 5162 [4.1]:
Strictly speaking, a server implementation that doesn't remember mod-
sequences associated with expunged messages can be considered
compliant with this specification. Such implementations return all
expunged messages specified in the UID set of the UID FETCH
(VANISHED) command every time, without paying attention to the
specified CHANGEDSINCE mod-sequence. Such implementations are
discouraged, as they can end up returning VANISHED responses that are
bigger than the result of a UID SEARCH command for the same UID set.
Clients that use the message sequence match data can reduce the scope
of this VANISHED response substantially in the typical case where
expunges have not happened, or happen only toward the end of the
mailbox.It also gives advice to avoid infinitely storing the modsequences such
as "expiring" sequences associated with older expunged messages, but
assigning a single modsequence value to all of the expired expunged
messages.
-- mike
The Horde Project (www.horde.org) mrubinsk@horde.org