[root@smail01 log]# echo "test" | mail -s testmessage chrisbare83@gmail.com
[root@smail01 log]# tail -f /var/log/maillog
Dec  5 18:04:38 smail01 postfix/smtp[29138]: 93C73240230: to=<chrisbare83@gmail.com>, relay=none, delay=1666, delays=1516/0.06/150/0, dsn=4.4.1, status=deferred (connect to alt2.gmail-smtp-in.l.google.com[2800:3f0:4003:c01::1a]:25: Connection timed out)
Dec  5 18:05:11 smail01 postfix/postfix-script[29520]: stopping the Postfix mail system
Dec  5 18:05:11 smail01 postfix/master[1477]: terminating on signal 15
Dec  5 18:05:13 smail01 postfix/postfix-script[29605]: starting the Postfix mail system
Dec  5 18:05:13 smail01 postfix/master[29606]: daemon started -- version 2.6.6, configuration /etc/postfix
Dec  5 18:05:13 smail01 postfix/qmgr[29609]: 946DD240231: from=<root@smail01.cellponds.com>, size=455, nrcpt=1 (queue active)
Dec  5 18:05:13 smail01 postfix/qmgr[29609]: 61A9C24022C: from=<none@yourpbx.com>, size=455, nrcpt=1 (queue active)
Dec  5 18:05:33 smail01 postfix/pickup[29608]: 12401240238: uid=0 from=<root>
Dec  5 18:05:33 smail01 postfix/cleanup[29676]: 12401240238: message-id=<20151206020533.12401240238@smail01.cellponds.com>
Dec  5 18:05:33 smail01 postfix/qmgr[29609]: 12401240238: from=<root@smail01.cellponds.com>, size=455, nrcpt=1 (queue active)
Dec  5 18:05:43 smail01 postfix/smtp[29611]: connect to gmail-smtp-in.l.google.com[74.125.21.26]:25: Connection timed out
Dec  5 18:05:43 smail01 postfix/smtp[29612]: connect to yourpbx.com[54.174.31.254]:25: Connection timed out
Dec  5 18:06:03 smail01 postfix/smtp[29678]: connect to gmail-smtp-in.l.google.com[74.125.21.26]:25: Connection timed out