Using sendmail


$ telnet localhost smtp
Connected to localhost.
Escape character is ‘^]’.
220 ESMTP Postfix
mail from:
250 2.1.0 Ok
rcpt to:
250 2.1.5 Ok
354 End data with <CR><LF>.<CR><LF>
250 2.0.0 Ok: queued as 8E00818F
221 2.0.0 Bye
Connection closed by foreign host.


Using mailx/mail

$echo "Test message body..." | mailx -s "TEST E-MAIL VIA MAIL/MAILX"
*** Please note these mail programmes should be installed on the Linux/Unix variant touse them, they may/mayn't be available or installed by default.

More email sending options here, nice blog.

Further reading..