Netscape Messenger

Your Name = fred
Email Address = fred@earthlink.net (your dialup email address)
Reply to = anything@fred.com (this can be your email address for your domain)
Mail Server username = fred
Outgoing Smtp = mail.earthlink.net
Incoming Smtp= anything@fred.com (this can be any email address you have setup for your domain)

To check numerous POP accounts, read the manual or help files that come with your email client software for configuration.