[Dovecot] Dovecot (IMAP) Hangs sometimes

[Mario Gomide]

Hi there!

I'm using Dovecot 1.0.7 in RHEL 5.4 64bits as a IMAP/POP3 server.

Dovecot authenticates users against an AD server via kerberos (pam
configuration) and clients connect to it via IMAPs and POP3s with SSL.
Webmail is in localhost and connects locally also with SSL.

All is fine and people use the email server normally and with no problems.

But, I have noticed that dovecot hangs sometimes. Usually twice a day
somewhere between 09:40 and 10:00 a.m and in the afternoon at about 3:00
p.m.

The problem starts when webmail takes long to authenticate and show folders
and stuff. After a while it times out and doesn't connect. Then the clients
(e.g. outlook, thunderbird) start taking long to connect and then they
timeout. Important: Only IMAP connections timeout! POP3 continues ok. This
latency keeps on going until dovecot finally hangs (after about 10 to 15
minutes). The problem is solved when I restart/reload dovecot.

I'm not sure as to what's going on! I check the log, but it has been hard to
pinpoint an exact event or to detect when the problem begins.

Any ideas?

BTW: what's the real difference between reload and restart?

Thanks a lot!
Mario