[Dovecot] TLS timeout with Thunderbird

I'm trying to get dovecot working with various clients on my new
mailserver. I installed the base rc2 that comes with OpenBSD 4.0,
then upgraded to rc14 when I ran into problems with TLS and
Thunderbird. The server has no problems with Mail.app on my laptop,
but any connection attempts from Thunderbird timeout after the TCP
handshake.

13:53:41.074438 66.x.x.2.50483 > 38.x.x.248.993: S
3787736038:3787736038(0) win 65535 0,nop,nop,timestamp 2064284084 0,sackOK,eol> (DF) 13:53:41.074554 38.x.x.248.993 > 66.x.x.2.50483: S
1565942120:1565942120(0) ack 3787736039 win 16384 1460,nop,nop,sackOK,nop,wscale 0,nop,nop,timestamp 2681405076
2064284084> (DF) 13:53:41.459434 66.x.x.2.50483 > 38.x.x.248.993: . ack 1 win 65535
(DF) 13:53:47.028621 66.x.x.2.50483 > 38.x.x.248.993: F 1:1(0) ack 1 win
65535 (DF)

The only thing logged by dovecot is a disconnection event. There is
nothing else logged, even with ssl_verbose enabled.

Nov 17 14:23:05 colo2 dovecot: imap-login: Disconnected: rip=66.x.x. 2, lip=38.x.x.248, TLS handshake

This happens with Thunderbird 1.5.0.4 and 1.5.0.8 on Mac OS X, and
Thunderbird 1.5.0.7 on Windows 2000. Any ideas would be greatly
appreciated.

Thanks,

-- Jason Dixon DixonGroup Consulting http://www.dixongroup.net