postfix in AWS to relay to IronPorts

I have setup postfix in AWS to relay to IronPorts .

 From time to time I have  "Connection timeout " especially when  more than 20 emails at the same moment. These messages deferred into queue. Eventually they being delivered - but with unacceptable delay .  

AWS server - RHE 7.2- M4 -Enhanced network 10Gig

IronPorts administrators said there is nothing on their side.
andrey_chevronAsked:
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andrey_chevronAuthor Commented:
Amazon put a limitation on port 25 by default. After throttle  was tunes everything is normal.
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ArneLoviusCommented:
Connection Timeout is too generic to be able to do any sensible diagnosis

I would suggest following the postfix debugging documentation

http://www.postfix.org/DEBUG_README.html

in particular "Verbose logging for specific SMTP connections" and "Record the SMTP session with a network sniffer"
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arnoldCommented:
Is your relay com big cludes authentication?
Are you replying all outgoing message through them?
Look at the /var/log/maillog to see when timeouts are reported .....
1) there is either a threshold on their side limiting number of connections from the same IP, or limits on connections/messages from the same source within a certain amount of time, where they introduce delays in response, but those delays exceed the connection timeout period set on your side.

Are the messages being denied destined to the same destination?
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andrey_chevronAuthor Commented:
I found it myself
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