52 lines
2.0 KiB
Plaintext
52 lines
2.0 KiB
Plaintext
MBOX-Line: From mrc+imap at panda.com Tue Jun 1 15:58:25 2010
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To: imap-protocol@u.washington.edu
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From: Mark Crispin <mrc+imap@panda.com>
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Date: Fri Jun 8 12:34:43 2018
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Subject: [Imap-protocol] Persistence of UIDs across moves
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In-Reply-To: <4C058BF2.22215.5F102940@David.Harris.pmail.gen.nz>
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References: <4C058BF2.22215.5F102940@David.Harris.pmail.gen.nz>
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Message-ID: <alpine.OSX.2.00.1006011543010.77397@hsinghsing.panda.com>
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On Wed, 2 Jun 2010, David Harris wrote:
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> * User moves a message from inbox to another mailbox.
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> * User moves the same message from the other mailbox back to the
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> inbox.
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> The question is, does IMAP expect that the message will have the
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> same UID after being moved back into the inbox?
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No.
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Once a message is expunged from a mailbox its UID is gone forever (at
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least as long as the UIDVALIDITY last).
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Now, if the "move" was implemented as copy+delete WITHOUT expunging the
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message in the source mailbox, then that message could be undeleted and
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thus retain the same UID. But in this case, it wasn't "moved back"
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(except perhaps in a users GUI); it was never expunged.
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However, that kind of "move" and "move back" would be a client-side
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implementation. A server has no latitude to make that kind of decision.
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> It is possible to read this as meaning that once any specific message
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> has been assigned a UID in a folder, it should always have that UID
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> any time it is replaced in that folder, until such time as UIDVALIDITY
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> changes.
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Fortunately, that reading is incorrect.
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Perhaps the text should have said "single immutable instance of a message"
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instead of "single immutable message".
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The incorrect reading would make sense in a world with global UIDs. IMAP
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does not have global UIDs. If it did, it would require the invalidation
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of either the property of strict ascendency of UIDs or the property that
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new messages always are appended to the mailbox sequence space (instead of
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inserted).
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-- Mark --
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http://panda.com/mrc
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Democracy is two wolves and a sheep deciding what to eat for lunch.
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Liberty is a well-armed sheep contesting the vote.
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