Exchange 2007 cannot send to some domains
Exchange 2007 SP2 Rollup 10 Windows Server 2003 R2 64-bit Exchange is a single server, no separate edge transport server. Problem: E-mail to certain domains are not delivered. The error in the queue shows a 4.4.2 "Connection dropped". Connection may also get dropped when using TELNET to test the connection. The disconnect always occurs at the RCPT TO: portion of the dialogue. When I first started investigating this problem, I discovered that our PTR record had disappeared. This was corrected, but the problem remains. Packet captures have shown the dialogue between servers always ends after the RCPT TO: is issued, but not always the address of the recipient. In any case, this is where the dialogue ends, and the connection times out. This is not a new server, and the problem just appeared one day. This is definitely not a high volume server--I'd say that if we hit a hundred outgoing messages a week, it would be a very busy week. I've gone through all the settings, and nothing seems to have changed there. There have been no additions or changes to the server recently, other than the usual MS patching and A/V updates (Exchange is excluded from the scanning). I've searched the web with no joy. The hits I hae gotten do not seem to apply to this particular circumstance, and, thus far, the fewer resolutions I have found and followed up on all show tha the "fixes" are already in place. We have even gone so far as to suggest building a new server, and a new install of Exchange, all the while crossing our fingers to hope that would resolve the issue. In the mean time we have a work around in plae in that we opened a free account, and we are directing replies back to the our server as we have no apparent issue with inbound mail. Any help, tips would be appreciated, a resolution would be prized. Thanks., \\Steve//
April 23rd, 2010 6:59pm

Hi Steve, Can you just try to enable anonymous access permission on Default receive connector and check the issue. What is method you are using to send mail to external users ?? Is it thru outlook ar via any application. Try to telnet to the SMTP servers for those domain and make sure that you are not listed and have correct MX and Reverse records. How you are sending message to external , is it poiting to any smart host or via DNS resolution.Anil
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April 24th, 2010 7:27pm

On Fri, 23 Apr 2010 15:59:05 +0000, Stevesz wrote: > > >Exchange 2007 SP2 Rollup 10 > >Windows Server 2003 R2 64-bit > >Exchange is a single server, no separate edge transport server. > >Problem: E-mail to certain domains are not delivered. The error in the queue shows a 4.4.2 "Connection dropped". Connection may also get dropped when using TELNET to test the connection. The disconnect always occurs at the RCPT TO: portion of the dialogue. That sounds like the behavior you'd see if your IP addres was in some DNSBL. Have you checked if it is? --- Rich Matheisen MCSE+I, Exchange MVP--- Rich Matheisen MCSE+I, Exchange MVP
April 25th, 2010 12:10am

Anonymous permission is enabled. Mail is being sent from Outlook with no other method used, except internally. As I mentioned, TELNET shows the same behavior, connection ends after RCPT TO: is issued. Actually, it times out, both through Exchange and TELNET. As mentioned, I did check the records and found the PTR record had disappeared, but that has been remedied. We are using DNS resolution. This behavior continues whether we are using local DNS or external DNS. \\Steve//
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April 26th, 2010 11:42pm

Rich, That was my first thought, based on the behavior of the servers for sent e-mail. A check of lists using MXTOOLBOX showed us on one such list--one that is not normally used since it blocks whole netblocks. The whole Class C we are one is blocked by them, Ostensibly for being a dynamic IP (false, it is static) or generic rDNS (this was true at the time as I looked into it, but the issue has been resolved). Despite several removal requests by myself and the ISP, the address is still listed there. This appears to be the only RBL we are listed on. We are even having problems with sending mail to our ISP's domains, though they could not tell us why this would be. \\Steve//
April 26th, 2010 11:54pm

On Mon, 26 Apr 2010 20:54:06 +0000, Stevesz wrote: >That was my first thought, based on the behavior of the servers for sent e-mail. A check of lists using MXTOOLBOX showed us on one such list--one that is not normally used since it blocks whole netblocks. The whole Class C we are one is blocked by them, Ostensibly for being a dynamic IP (false, it is static) or generic rDNS (this was true at the time as I looked into it, but the issue has been resolved). Despite several removal requests by myself and the ISP, the address is still listed there. This appears to be the only RBL we are listed on. > >We are even having problems with sending mail to our ISP's domains, though they could not tell us why this would be. Well, I suppose you could get a network monitor trace of what's going on (WireShark is what I usually use). If the "three-way handshake" completes and the connection drops after that the ISP should be able do the same thing at their end (probably with their firewall logs) and tell you if they reset the connection. If they did, well, then they should be able to tell you why they did it. It's a good thing to keep in mind that DNSBLs aren't the only reason for connections being dropped. Some security devices will keep track of activity and automatically block connections if they detect abnormal levels of spam-like behavior (e.g. directory harvesting, large numbers of bad e-mail addresses, etc.). --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP
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April 27th, 2010 4:51am

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