POP3 (Post Office Protocol 3) is the current version of a standard protocol for receiving email. It is used by most ISP and mail servers. It's function is very much like a P.O. Box at your local post office. Like the P.O. Box it holds you mail until you pick it up. Programs like Outlook, Outlook Express, Eudora, Fox mail and numerous others will pickup your mail from a POP3 account.. To pickup the mail for the whole company you want to look at tools like SMTPBeamer and POPBeamer.