Howto become a hosting service company? :-)

If you experience problems using MS pop service on Win2003, give a chance to
“Free Pop/Smtp Email Server Application”

Fighting against blacklist inclusion
Sending Bulk Mail Messages with Inline Image Attachements
Send an Email in C# with Inline attachments with System.Web.Mail (old way)
How do I embed images in an email? with System.Net.Mail (new way)
Reading EML Files and Sending as Email in C#
Getting mails from mail server