Palm T/X Handheld: Versamail Receives Mail But Can't Send

I have a Palm T/X handheld that I use to access my Mac Mail account via Wifi. Using Versamail, I can get my mail fine from the Mac server but when I try to send a message, I get the following VersaMail error message:

VersaMail Error 535 5.7.0 Authentication Failed

My VersaMail settings are as follows:

Account Name: mac email
Mail Service: US-Apple .Mac
Protocol: IMAP
User name: my email address
Password: my email password
Incoming Mail Server: mail.mac.com
Outgoing Mail Server: smtp.mac.com
Incoming Port Number: 143
Use SSL: NOT checked
Outgoing Port Number: 25
Use SSL: NOT checked
Use ESMTP authentication: Checked

What am I doing wrong and how do I fix it?

Thanks.


Power Mac G5 Quad@2.5GHz; 4GB RAM Mac OS X (10.4.8) FCP 5 (FC Studio)