[Dovecot] Dovecot vs.Clients - strange behaviour, diagnostics sought

[Jeroen Scheerder]

I've been experimenting with dovecot-1.0-stable on Solaris.  Storage format 
is mbox.  Dovecot, in test, runs in parallel with an UW IMAP, with dovecot 
running SSL-only on port 994.

It seems to work to some extent:

	* dovecot runs
	* authentication works
	* SSL works
	* all manual IMAP functionality checks seem to work fine

However, I'm running into issues with IMAP clients.

* Null client: I started by using telnet as a client, and talking IMAP
   manually.  Seems OK.

* Mutt: "mutt -f imap://my.imap.server:994" seems to work well, although
   mutt keeps reporting details about the SSL certificate,  informs me that
   it belongs to the proper server and is a valid Globalsign-issued
   certificate -- and keeps insisting I either reject it or accept it
   once.

* Apple Mail (Panther's version, 1.3.11 (v622)) works, though it seems
   to have problems with large mailboxes.  Then again, it had these same
   problems with other IMAP servers as well.

* Thunderbird doesn't work at all.  After some waiting, it bums out and
   reports:

     Unable to connect to your IMAP server.  You may have exceeded the
     maximum number of conenctions to this server.  If so, use the
     Advanced IMAP Server Settings dialog to reduce the number of
     cached connections.

   Note that it never even shows an authentication dialog, and the
   only thing I see in dovecot's log that relates to Thunderbirds
   attempt is:

     dovecot: Jul 20 09:41:09 Info: imap-login: Disconnected: \
     Inactivity [131.211.143.87]

I'm at a loss as to what's causing this.  On the one hand, dovecot
seems operational, on the other hand at least one client can
do nothing with it.

All debugging/logging options are enabled.  What am I missing?