DBMail fails after first IMAP connection

So as of now DBMail appears to deliver mail, but I can't for the life of
me log in. In particular, Thunderbird seems to make one initial
connection on account setup, then absolutely fails in the future and I
see nothing in the logs.

I then tried telneting to my IMAP server. Whereas initially I get a
banner, after Thunderbird fails to connect I get absolutely nothing.

Here is a dbmail.err with log levels set to 511.

https://dl.dropboxusercontent.com/u/147071/dbmail.err

That should show numerous Thunderbird connection attempts, but it
doesn't. This is under DBMail 3.2.0.

Thoughts on what's going on here? I'll probably sink another day into
this before I need to switch to something that lets me authenticate. I'd
like to get this going if I can, as it seems like it could be a neat
solution.