[plt-scheme] IMAP message positions

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Mon Nov 11 18:24:37 EST 2002

At Mon, 11 Nov 2002 18:14:53 -0500 (EST), dvanhorn at emba.uvm.edu wrote:
> When an IMAP connection is established, is it guranteed not to be
> updated until a reselect? That is, can you rely on message positions
> to remain constant during a connection?

I don't think the IMAP standard provides such a guarantee. Indeed, IMAP
doesn't seem to be designed for concurrent access to a given mailbox.

Good IMAP servers seem to drop the old connection to a particular
mailbox, if any, when a new connection selects the mailbox.

The IMAP server currently running at Utah does not seem to be a good
one. Consequently, SirMail is in some ways designed around the problem.
But it's still possible to mess up by deleting messages from multiple
clients simultaneously, and I don't see a way around it, even in theory
(i.e, within the IMAP protocol). This hasn't been a problem in
practice, because I rare sit in front of two SirMail-running machines
at once.


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