Mac OSX Thunderbird 3

Enter your name, email address and password at the "Mail Account Setup" dialog. Then select continue. IMAP Mac Thunderbird frame 1
Once the dialog expands click on the stop button. Fill in mail.dcn.davis.ca.us for both the incoming and outgoing server. Select IMAP as the incoming mail server type. The incoming mail server port should be 993 and the outgoing server port is 25. Select SSL/TLS for the incoming server and STARTTLS for the outgoing server. IMAP Mac Thunderbird frame 2
Next click the "Re-test Configuration" button, then the "Create Account" button. IMAP Mac Thunderbird frame 3