We are unable to send mail to some domains (including but not limited to msn, hotmail and live). This problem began about a week ago with no changes to our configuration.
Messages sit in the smtp queue until they expire and I receive smtp 4.4.7 responses:
The following recipient(s) cannot be reached:
firstname.lastname@example.org on 6/11/2010 3:06 AM
Could not deliver the message in the time limit specified. Please retry or contact your administrator.
We appear to be receiving all inbound mail without difficulty.
Our configuration is as follows:
Single Exchange Server 2003 (mail.eastbrookhomes.com 188.8.131.52) routing to a Postini SmartHost (outbounds7.obsmtp.com)
Mx records point to Postini servers:
10 eastbrookhomes.com.s7a1.psmtp.com 184.108.40.206
20 eastbrookhomes.com.s7a2.psmtp.com 220.127.116.11
30 eastbrookhomes.com.s7b1.psmtp.com 18.104.22.168
40 eastbrookhomes.com.s7b2.psmtp.com 22.214.171.124
I have used several tools to verify that we are not on any known blacklists
I was able to send a message successfully via telnet to live.com from the mail server
I tried removing postini as the outgoing smarthost with no change.