[Dovecot] IMAP Clients can not see 3rd tier nested IMAP directories

[jjs87 at cornell.edu]

I have a very bizarre problem that I hope someone can help me with. I am 
not sure if this is a Dovecot problem, or IMAP client problem.

I recently used Transend's Migrator to move mail from Exchange 2007 to 
my Dovecot 1.0.7 server. The program seems to have moved the nested IMAP 
dirs properly as seen below in a directory listing of the maildir dir. 
The nested dirs have indexes, cur, new dirs as expected.

However, when the account is viewed in Windows Thunderbird 3.1.6 or 
Outlook 2010 the 3rd tier dirs are not seen, nor can they be subscribed 
to. On a whim, I decided to try Apple Mail 4.3 to view the account and 
all the IMAP dirs can be seen and accessed as expected.

Any idea what is going on?  Is this somehow an IMAP client problem (bug) 
or an issue with Dovecot and these clients?


Listing of the Maildir dir:

[root Maildir]# ls -al
total 92
drwx------ 17 andrew andrew  4096 Dec  6 17:06 .
drwx------  9 andrew andrew  4096 Dec  6 15:58 ..
drwx------  5 andrew andrew  4096 Dec  6 16:31 .mailbox
drwx------  5 andrew andrew  4096 Dec  6 16:31 .mailbox.mail
drwx------  5 andrew andrew  4096 Dec  6 16:48 .mailbox.mail.colleagues
drwx------  5 andrew andrew  4096 Dec  6 17:02 .mailbox.mail.colleagues.amy
drwx------  5 andrew andrew  4096 Dec  6 16:48 
.mailbox.mail.colleagues.aslan
drwx------  2 andrew andrew  4096 Dec  6 16:31 cur
-rw-------  1 andrew andrew   144 Dec  6 16:31 dovecot.index
-rw-------  1 andrew andrew 10272 Dec  6 16:31 dovecot.index.cache
-rw-------  1 andrew andrew   128 Dec  6 16:31 dovecot.index.log
drwx------  2 andrew andrew  4096 Dec  6 16:31 new
drwx------  5 andrew andrew  4096 Dec  6 16:53 .Sent Items
-rw-------  1 andrew andrew    32 Dec  6 17:06 subscriptions
drwx------  2 andrew andrew  4096 Dec  6 16:31 tmp
drwx------  5 andrew andrew  4096 Dec  6 16:32 .Trash


PROBLEM:

When viewed in Thunderbird 3.1.6 or Outlook 2010:

These nested dirs are seen:
..mailbox
....mail

These nested dirs are NOT seen or can be subscribed:
......colleagues
........amy
........aslan


OBSERVATIONS:

When viewed in Apple Mail 4.3, all dirs are seen correctly.

Thank you, I appreciate any and all replies, comments, questions, and 
suggestions.
Jason