[Dovecot] pop3_lock_session question

[Justin Krejci]

> > Could it be some (older?) webmail clients that use pop3 instead of imap?
>
> I wouldn't expect a webmail client to hold a pop3 connection open
> across multiple web requests.  We have standard webmail clients
> available for customer use, but they use IMAP.  With the frequency
> we're seeing this problem, I'd expect it's more likely to be something
> newer or more commonly used.

Presuming you've been able to identify which users this is affecting I would
suspect you could go back to those users and determine what clients they are
connecting with and then interested parties (dovecot devs?) could perform
further investigation in a lab or whatever to determine what is going on.
Maybe the client(s) is/are just whacky or there is a bug somewhere.

You can also track down the source IP addresses which may give you an idea
as to the client as well. If it is a RIM subnet then you may be able to
assume it's a blackberry. If the PTR record for the IP is
webmail.somecompany.com then you can probably contact the company and
discuss with them. Etc. Some companies may have a proxy or something that is
attempting to hold the connections open for faster response times maybe
geared for slow link connections. People do a lot of "interesting" things
from time to time.

I also didn't see you mention it but presumably you are on a relatively
recent version of Dovecot considering you are examining the source code.