echo ``it works'' | mail class -s''it works''which will create a piece of mail and save it in ``/var/spool/postfix/maildrop''.
Note that mail you send will not actually arrive until some program processes the mail in the maildrop file. There are programs that read the maildrop file and distribute the outgoing mail to user's mailboxes. They also listen to the network and receive incoming mail. Such programs are called ``Mail Transfer Agents'' and we mention a few below.