I have postfix on CentOS6.6 on my local server(192.168.1.103), from which I'm unable to send emails to any domains.
The following is the error obtained when sent to our company email.:
Jun 2 11:09:55 server postfix/error: 3392D5418AC: to=, relay=none, delay=73765, delays=73765/0.03/0/0.09, dsn=4.4.2, status=deferred (delivery temporarily suspended: lost connection with yyy.com[192.254.abc.def] while receiving the initial server greeting)
This is the error when sent to a gmail address:
Jun 2 11:11:26 server postfix/smtp: connect to gmail-smtp-in.l.google.com[2404:6800:4003:c00::1a]:25: Network is unreachable
Jun 2 11:11:38 server postfix/smtp: 519B054193B: to=, relay=gmail-smtp-in.l.google.com[22.214.171.124]:25, delay=13, delays=0.11/0/3.4/9.8, dsn=5.7.1, status=bounced (host gmail-smtp-in.l.google.com[126.96.36.199] said: 550-5.7.1 [188.8.131.52] The IP you're using to send mail is not authorized to 550-5.7.1 send email directly to our servers. Please use the SMTP relay at your 550-5.7.1 service provider instead.
This is the command I use to send email from my server:
echo "Test mail from postfix" | mail -s "Test Postfix" firstname.lastname@example.org