Stupid question regarding Thunderbird and IMAP

[Jason Stephenson]

You seem to have already gotten answers on your problem and I hope that 
they work for you.

Something I'll add is that when building UW Imap (boo hiss! I hear you 
jeer), I've had to use the WITH_NETSCAPE_BRAINDAMAGE option to get IMAP 
to work properly with Mozilla and Mozilla-based mail programs.

I don't know if the above applies to dovecot, but since the email 
programs you mentioned having trouble are Mozilla-based (except for 
squirellmail), I thought that I might throw this out there.

Fortunately for me, the users at my day job aren't sophisticated enough 
to want folders within folders on their IMAP accounts.