[POLL] pop3d/nntpd and IMAP flags

Joseph Brennan brennan at columbia.edu
Tue Oct 25 13:14:52 EDT 2005

Ken Murchison <murch at andrew.cmu.edu> wrote:

> It would be fairly straightforward to have an option that updated \Seen
> state whenever a POP3 client issues a RETR command or an NNTP client
> issues a BODY or ARTICLE command.

I'm on the fence whether this makes sense for POP.  But we've used
U Wash for a long time and marking them as seen has not raised any
questions that I can recall, so that behavior must be what users
expect or accept.

> My question is what do people think of the interaction between
> pop3d/nntpd and the \Deleted flag?  Should these daemons ignore articles
> that have this flag set?  Should a POP3 DELE command or a NNTP cancel
> message just set the \Deleted flag instead of expunging the message?

The RFC for POP3 actually describes DELE to mean mark as deleted, and
QUIT to mean expunge and quit.  I have just learned after all these
years that if QUIT is not sent, the server 'MUST' not expunge.  But
does any client make this optional?  The braintwister is that POP
mark deleted and IMAP mark deleted don't need to be the same thing,
so maybe POP expunge and IMAP expunge don't need to be the same thing

The practical problem is that POP-only users would have no way to
really expunge if DELE and QUIT don't do it, so they'd accumulate
mail until they run out of quota.  And then what do they do?

This touches on the infamous problem of users who blow away their inbox
accidentally by using a POP3 client that defaults to DELE on server.
It's tempting to mark deleted to solve that.  But it seems to me only
to trade one problem for another.  What we need is user-controlled
unexpunge, Ken!

Joseph Brennan
Columbia University Information Technology

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