[Dovecot] sporadic slow/non response, problems copying to sent folder

[Danno Coppock]

After experiencing these symptoms through many of the release 
candidates, we've been at v1.0.0 now for a few weeks, and they're still 
there.  Perhaps a config issue with my setup (mbox locks?).  It's really 
too disrupting to continue using this way.  I've included symptoms, 
client info, mta info, log entries and config file.  What other 
information can I provide?  Please advise.

Thanks, Danno

symptoms:

  1. Coming back to the idle client, and clicking on a newly arrived 
message, often a long delay (seems like minutes, sometimes) will occur 
before the message loads from the server.
  2. Sending messages, as often as not, the client will stall, sometimes 
indefinitely, on "copying message to sent folder".

client:

   * usually not more than 2-3 clients running at any time.
   * Thunderbird 1.5.0.10 (on XP)
   * Thunderbird 1.5.0.5 (on FreeBSD 5.5)

mta:

   * Sendmail 8.13.6/8.13.6
   * $sudo sendmail -bt -d0.10 < /dev/null | grep HASFLOCK
         OS Defines: BSD4_4_SOCKADDR HASFCHOWN HASFCHMOD HASFLOCK

=== log entries
May  3 21:27:09 tejas dovecot: imap-login: Login: user=<annie>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 21:28:00 tejas dovecot: IMAP(annie): Disconnected
May  3 21:28:01 tejas dovecot: imap-login: Login: user=<annie>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 21:32:08 tejas dovecot: IMAP(annie): Disconnected for inactivity
May  3 21:37:01 tejas dovecot: IMAP(annie): Disconnected
May  3 21:37:02 tejas dovecot: imap-login: Login: user=<annie>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 21:37:55 tejas dovecot: IMAP(annie): Disconnected in IDLE
May  3 21:38:18 tejas dovecot: IMAP(annie): Disconnected in IDLE
May  3 21:56:02 tejas dovecot: imap-login: Login: user=<danno>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 21:56:17 tejas dovecot: IMAP(annie): Disconnected for inactivity
May  3 21:58:32 tejas dovecot: IMAP(danno): Disconnected
May  3 22:02:31 tejas dovecot: imap-login: Login: user=<danno>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 22:03:14 tejas dovecot: imap-login: Login: user=<danno>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 22:14:10 tejas dovecot: IMAP(annie): Disconnected
May  3 22:14:38 tejas dovecot: IMAP(danno): Disconnected in IDLE
May  3 22:16:24 tejas dovecot: imap-login: Login: user=<danno>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 22:16:33 tejas dovecot: imap-login: Login: user=<annie>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 22:16:44 tejas dovecot: imap-login: Login: user=<annie>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 22:18:36 tejas dovecot: imap-login: Login: user=<annie>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS
May  3 22:19:16 tejas dovecot: IMAP(danno): Disconnected
May  3 22:19:17 tejas dovecot: imap-login: Login: user=<danno>, 
method=PLAIN, rip=71.216.71.193, lip
=68.224.168.249, TLS

===== config
$grep -E -v '^ *(#|$)' dovecot.conf
protocols = imaps
login_process_size = 64
default_mail_env = mbox:~/mail/:INBOX=/var/mail/%u
mail_extra_groups = mail
verbose_proctitle = yes
first_valid_uid = 100
first_valid_gid = 0
mbox_read_locks = flock
mbox_write_locks = flock
protocol imap {
 imap_client_workarounds = delay-newmail outlook-idle netscape-eoh 
tb-extra-mailbox-sep
}
protocol pop3 {
 pop3_uidl_format = %08Xu%08Xv
 pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}
protocol lda {
 postmaster_address = postmaster at example.com
 sendmail_path = /usr/sbin/sendmail
}
auth default {
 mechanisms = plain
 passdb pam {
 }
 userdb passwd {
 }
 user = root
}
dict {
}
plugin {
}