[Dovecot] Just one user experiencing server timeouts

[Fran Fabrizio]

[dovecot-1.0-0.beta2.7 on Fedora Core 5, maildir formatted mail 
directories, various clients: thunderbird 1.5.0.4 from FC4 and WinXP, 
SquirrelMail 1.4.6-5.fc5 RPM, various recent versions of Pine from 
various Fedoras and Redhat 9]

I have just one mail user who experiences server timeouts when trying to 
delete a message (move it to Trash) or other common operations.  This 
user has 4.1GB of mail spread over 200+ Maildir-formatted folders, so I 
immediately expected sheer volume as the problem - this user has by far 
the most mail.  This user experiences the problem from multiple 
Thunderbird installs, from SquirrelMail, and from Pine.

However, I created a new user account using our standard account 
creation processes, and did a direct copy of olduser's Maildir to 
newuser's homedir.  Then I did a chown -R newuser ~newuser/Maildir, set 
up an account in Thunderbird for newuser's account, and tried for an 
hour to get a server timeout doing all the same operations that cause 
the timeout on olduser's account, with no timeouts.  I absolutely cannot 
duplicate the behavior, but when I watch olduser do this from any of the 
above named clients, I see the timeouts on about 10% of the operations.

I've been looking into this off and on for weeks, but I am baffled.  I 
can't think of what is so specific about this one user's account that is 
causing the trip up.  Both home directories are stored on the same 
filesystem and as I mentioned I made an exact duplicate of Maildir.  I'm 
completely out of ideas, does anyone have any thoughts?  Does Dovecot do 
any data tracking on a per user basis that could be confusing it, some 
cache I can clear?  Dovecot has been restarted numerous times since the 
trouble started.

-- 
Fran Fabrizio
Senior Systems Analyst
Department of Computer and Information Sciences
University of Alabama at Birmingham
http://www.cis.uab.edu/
205.934.0653