I have postfix on CentOS6.6 on my local server(, 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[23443]: 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[23507]: 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[23507]: 519B054193B: to=, relay=gmail-smtp-in.l.google.com[]:25, delay=13, delays=0.11/0/3.4/9.8, dsn=5.7.1, status=bounced (host gmail-smtp-in.l.google.com[] said: 550-5.7.1 [] 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" [email protected]

Any suggestions?


1 Answer 1


This is happening because your IP is listed on a few popular black lists. You can check that on mxtoolbox.com.

Also note that your MTA's IP does not have neither a forward (A) or reverse (PTR) DNS records which is a good reason for them to get rejected by other MTAs in the first place.

In this world of spammers, MTAs need to be extremely careful on what other MTAs they deal with.

Managing an MTA is not a simple task and you should therefore leave it to the professionals and use your hosting provider's service.


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