I have a new mail server running courier-imap 4.5.0 on Solaris 10u7, 
with home directories and maildirs (Maildir format) mounted using 
autofs. Clients connect via SSL(only) using a variety of mail clients 
(although I'm seeing the behavior on both sylpheed and thunderbird 
specifically). The primary back-end file server is a netapp running NFS, 
connected via gigE across a cisco switch. Neither the server nor the 
netapp are reporting any kinds of errors or stress, and traffic is way 
under what I've been able to get with direct copies. I've got 
MAXDAEMONS=250 and MAXPERIP=50 (probably excessive, but shouldn't cause 
a problem), neither of which is even being scratched (about 150 daemons 
during peak times).

The only problem is, it seems like Copy operations are very slow for the 
first 30-45 seconds of a given imap session, sometimes to the point 
where you only can do one operation before it gets better (i.e. copying 
a small mail to the sent folder takes 30 seconds). It seems to happen 
every time a given user reconnects after about 30 minutes of inactivity 
(I'm guessing its after the old connection shuts down, because thats 
about the right time frame). It doesn't feel like mount or 
authentication overhead though, since most times the user is able to log 
in, browse their messages, and then initiate a copy operation(copy to 
sent folder, folder to folder copies, or move to trash all exhibit this) 
before it hangs waiting for the operation to finish. Also, I run 
squirrelmail on the same server, although it connects to localhost 
without SSL, and have had no reports of any slow downs what-so-ever on 
squirrelmail.

I've read over pretty much everything I could find about things that 
could slow courier down, and nothing seems to be jumping out at me. I'm 
not using FAM/Gamin; no high resource utilization; no network overload; 
keywords are turned on, but none of the users have massive keyword 
:lists. As you might be able to tell, I'm at a total loss as to what 
could be causing this.


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