[myusername@myhostname ~]$ echo "test" | mail -s test myrealmail@gmail.com
[myusername@myhostname ~]$ sudo tail -30 /var/log/mail.log
Mar  8 20:17:27 localhost postfix/postfix-script[4998]: starting the Postfix mail system
Mar  8 20:17:27 localhost postfix/master[4999]: daemon started -- version 2.9.1, configuration /etc/postfix
Mar  8 20:18:41 localhost postfix/pickup[5000]: CE6F7301419: uid=1000 from=<milos>
Mar  8 20:18:41 localhost postfix/cleanup[5024]: CE6F7301419: message-id=<20120308191841.CE6F7301419@myhostname.dyndns.org>
Mar  8 20:18:41 localhost postfix/qmgr[5001]: CE6F7301419: from=<myusername@myhostname.dyndns.org>, size=454, nrcpt=1 (queue active)
Mar  8 20:18:43 localhost postfix/smtp[5026]: CE6F7301419: to=<myrealmail@gmail.com>, relay=smtp.gmail.com[74.125.79.108]:587, delay=1.7, delays=0.11/0.01/0.8/0.78, dsn=2.0.0, status=sent (250 2.0.0 OK 1331234322 o11sm9362495eef.4)
Mar  8 20:18:43 localhost postfix/qmgr[5001]: CE6F7301419: removed