THANK YOU! This actually worked. The person that was having problems with thier Thunderbird posted the steps they took as well. Very easy to do.

For those that may need the info:

In Thunderbirds Account Settings, Set ALL Incoming Mail servers to:
127.0.0.1

Then set all of your user names to yourusername#mail.whatever.com

For outgoing SMTP set it to 127.0.0.1 and use the same username format.
username#smtp.whatever.com

Works wonderfully.