It seems like the problem has to do with having a default domain suffix set. Say your cable modem's domain name is yourdomain.com. When you set up for DHCP, you will get assigned the domain suffix of your ISP as your default domain to search on. So when your mail server is set at "mail", it's actually searching mail.yourdomain.com. However, when you specify a static IP, you must specify this information yourself--either you can set it in your email program to check mail.yourdomain.com--or change it globally in your TCP/IP settings (in Win95/98, it's under the DNS configuration tab, and type it in Domain Suffix Search Order.) Ok, I hope that answers your question.