Configuring Mail Applications
The basic settings for these should be:
Mail Server: YourDomain.com or mail.YourDomain.com
SMTP: YourDomain.com or mail.YourDomain.com
Username:
Password:
Troubleshooting:
If these settings do not work for you, then the ISP you use to connect to the Internet has most likely blocked Port 25, so you cannot use your own mail server for OUTGOING mail (SMTP) while connected via their network. Some of the ISPs who do this are Earthlink/Mindspring, AOL, USA-Starnet, and MSN. Microsoft, for example, gives an explanation (as regards to their own blocking) and solution:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q302339
The solution is to use your ISP's SMTP settings for outgoing mail (in the case of MSN this is 'smtp.email.msn.com'). BUT MAKE SURE TO KEEP YOUR DOMAIN AS THE MAIL SERVER FOR INCOMING MAIL!