Mail user-agent programs

Before you can use the mail system, you must select a user-agent program. You can choose a mail program (mail), message handler (mh), or the bellmail command.

A user-agent program provides facilities for creating, receiving, sending, and filing mail. In addition, you need a transport-agent program, sendmail, which distributes incoming mail from other systems or packages and distributes each outgoing mail item and then transmits it to a similar program in one or more remote systems.

Note: The mail and mh programs are incompatible in the way they store mail; you must choose one mail handler or the other.