POP3 locking. Is there a way to reduce this "issue"?

Jose Perez jvoorhees1 at gmail.com
Mon May 18 21:22:52 EDT 2009

Hi there:

I'm having problems with POP3 locking. I already read the forums and
info-cyrus mail archives talking about this but I didn't find a
solution yet:

- RFC states that is it necessary a minimum of 10 minutes before
detect a timeout on the client
- RFC states that only one connection is possible at the same time.
- Restarting Cyrus IMAP it could solve POP3 locking in that moment,
but it could happen again soon
- MUA's like Outlook or others aren't exactly the source of problem
since this ocurred with other e-mail clients
- Searching and killing the process of pop3d that is locking a user
connections could be a solution, but again... it could happen soon one
more time
- Apparently the source of this "issue" could be network connectivy
problems: maybe clients before slow PPP connections or something
simliar could be affected by broken connections while POP3 Server
(cyrus imap) thinks that the other connection is still alive and so
keeps the locking active for at least 10 minutes (minimum timeout)
- We can't decrease the value of poptimeout option in imapd.conf
without change source code and recompiling Cyrus because of the nature
of POP3 protocol.

I think I was googling around enough to get this info (above) and
understand that this isn't a POP3 problem exactly, that's the normal
way of POP3 behavior.
Some people could just say "don't use POP3 anymore, use IMAP" right?
Ok, I'd say the same as a sysadmin but you know exactly that this
isn't always possible is some organizations for others reasons not

What I would like to know is:

Are there some tips/tricks/configuration/magic/tutorial/howto/recommendation/etc
that we can follow to reduce this POP3 locking in some users? I'm
having this more frequently with users that get e-mail trough
Blackberry according to mail logs.

I hope someone could share its experiences, ideas and suggestions of
how to reduce this issue. Maybe it could be something at the server
level or maybe at the user level.

Any help will be appreciated, thanks.


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