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usually my posftix/smtp works fine until now, it get timed out on almost every destinations.

I drop all the firewalls, and start to accept all. I check the firewall. and there is no problems.

$telnet a.mx.mail.yahoo.com 25
Trying 67.195.168.31...
Connected to a.mx.mail.yahoo.com.
Escape character is '^]'.
220 mta145.mail.ac4.yahoo.com ESMTP YSmtp service ready

but in the log, i see this:

Oct 13 13:13:55 ubr postfix/smtp[4003]: connect to yahoo.com[98.137.149.56]:25: Connection timed out
Oct 13 13:14:25 ubr postfix/smtp[4003]: connect to yahoo.com[67.195.160.76]:25: Connection timed out
Oct 13 13:14:55 ubr postfix/smtp[4003]: connect to yahoo.com[72.30.2.43]:25: Connection timed out
Oct 13 13:15:25 ubr postfix/smtp[4003]: connect to yahoo.com[209.191.122.70]:25: Connection timed out
Oct 13 13:15:55 ubr postfix/smtp[4003]: connect to yahoo.com[69.147.125.65]:25: Connection timed out
Oct 13 13:15:55 ubr postfix/smtp[4003]: E94B74B8C: to=<WHOWHO@yahoo.com>, relay=none, delay=154369, delays=154219/0.03/150/0, dsn=4.4.1, status=deferred (connect to yahoo.com[69.147.125.65]:25: Connection timed out)

I Try to test the resolved ip for yahoo.com in the log.

$telnet 209.191.122.70 25 Trying 209.191.122.70...

Yes they timed-out

What did happend? It happend on

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2 Answers 2

up vote 0 down vote accepted

Timeouts like this can be a sign that you're being greylisted. Its a way some antispam systems use to slow down spammers by tying their outbound connections in a connection-timeout. You should check to see if your source IP address is showing up in any RBLs. Finding out if you're on any of the private lists can be a lot trickier.

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my ip is 114.129.16.35, and I didn't find it in RBLs –  Ta Coen Oct 13 '10 at 5:49
1  
I find, that postfix doesn't use the ip from MX, it use the ip from A. now how tho solve this? –  Ta Coen Oct 13 '10 at 6:08
1  
Please post you dns related stuff from /etc/resolv.conf. Your DNS server list may be outdated. Try with a public one from opendns or google. –  Paul Oct 13 '10 at 7:34
1  
I add disable_dns_lookups = no at the end of my main.cf, and the problem solved. –  Ta Coen Oct 15 '10 at 16:08

I had experiance the same as you.

If you have 2 nics, you should check which interface is listning for smtp. In my case, our server has two nics and private IP was listning for smtp.

And I have modified main.cf from inet_interface = 172.24.0.1 to inet_interfaces = all.

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