knowledge base

Details:

From the "Tools" menu, choose "Email Accounts"
Select "View or change existing email accounts"
Select the desired email account if you have more than one
Click the "Change" button
Change the SMTP server to mail.yourdomain.tld (Instead of  yourdomain.tld 
use your actual domain.)
Click  the "More Settings" Button
The SMTP Server requires authentication. (It does not use 
Secure Password Authentication (SPA)
Use your email address for the User Name
Use your email password for the Password
Once you change this, you need to go back in and change the SMTP port to 
587 (This is set in the "Advanced" tab)
Click Finish

Note: The Test Account Setting button on Outlook 2003 
registers false negatives. Though Outlook may think it will not work, it does. This 
may have been fixed in newer versions.

You should be able to send email.