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I have inherited a Fedora 10 machine running Postfix 2.5.6. Everything has been working well (all emails going out) up until about 3 weeks ago. I have been receiving complaints mail not getting delivered in a timely manner. Very new to Linux. I looked in the log files and I am seeing many lines like this. (blanked out email address)

Line 19168: Feb  5 09:21:54 fedora postfix/error[4303]: EF712966073: to=<>, relay=none, delay=1050, delays=1050/0/0/0, dsn=4.4.2, status=deferred (delivery temporarily suspended: lost connection with[] while sending RCPT TO)

I message will often get 1 or 2 of these and then finally go out. I have been hunting around on the net - but to no avail. Thanks in advance for your time - I appreciate it.

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I'd be more worried about having a publicly-accessible Fedora 10 system. There haven't been any security updates to Fedora 10 since December 2009. – mricon Feb 5 '13 at 18:10
Can you contact the smtp provider (obsmtp) and see if they've done any sort of security upgrades? It's entirely possibly they've made configuration changes to reject traffic from servers older than xxxxx. – Stephan Feb 5 '13 at 19:04

Not a particularly helpful error message, but it is pretty straightforward. lost connection with Figure out why it's losing the connection - that's going to come down to basic troubleshooting skills and log-diving.

For what it's worth, in the interests of to helping myself out down the line, I'd "figure it out" in a way that would involve me replacing that dinosaur with a server running a modern version of CentOS.

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Thanks for your help. – Jeff J. Feb 5 '13 at 18:28

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