Okay experts, I have a question for you.Recently we have upgraded from an Exchange 5.5 server to Exchange 2003. This was not a migration. We deployed a new server in a new domain.We have gone through the process of changing our RDNS with our ISP so that lookup resolves correctly. I've contacted AOL and they said we are no longer IP blocked. For some reason there are still some domains that we can't send/recieve from. Not all, most are working just fine. AOL still will not work and there are others here and there that simply don't come into our server. I've used SMTPDIAG and also tried manual transactions via telnet to no avail with AOL.The other parties will sometimes receive an NDR, sometimes they don't. It's a really frustrating situation. Any ideas? Any logging you wish to see? I can try and get whatever it may require to get this taken care of.Thanks in advance.

Hi, It would be usefull to see the NDR that is sent sometimes. Change the e-mail address in the ndr to protect the innocent. Leif

Here's what I've received from testing: p.MsoNormal, li.MsoNormal, div.MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:11.0pt;font-family:'Calibri','sans-serif';} a:link, span.MsoHyperlink {color:blue;text-decoration:underline;text-underline:single;} a:visited, span.MsoHyperlinkFollowed {color:purple;text-decoration:underline;text-underline:single;} .MsoChpDefault {;} @page Section1 {size:8.5in 11.0in;margin:1.0in 1.0in 1.0in 1.0in;} div.Section1 {page:Section1;} Your message did not reach some or all of the intended recipients. Subject: test Sent: 2/15/2008 10:52 AM The following recipient(s) cannot be reached: user@aol.com on 2/17/2008 11:05 AM Could not deliver the message in the time limit specified. Please retry or contact your administrator. <mail.cityofholland.com #4.4.7>

Here's what happens during a manual transaction with telnet to mailin-01.mx.aol.com220-********************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************EHLO cityofholland.com500 SYNTAX ERROR, COMMAND UNRECOGNIZEDHELO cityofholland.com500 SYNTAX ERROR, COMMAND UNRECOGNIZEDI have no idea why this happens. Same result on any smtp telnet connection, even domains that do work.

Hi, This should help: http://support.microsoft.com/kb/295725/en-us Leif

Thank you very much! That seems to have fixed a lot of issues we were having. All outbound mail is working now.The only problem left seems to be receiving from specific domains. Any other ideas?

Hi, I need to know what happens to mails from these domains. Leif

I received a fax about an e-mail that couldn't come through finally. It said:********@cityofholland.com (450 <********@pfm.com>: Sender address rejected: Domain not found)I've checked our DNS over and over on dnsstuff.com and also checked our MX records with mxtoolbox.com and everything checks out fine. Again, all the large corporations and e-mail systems can get through, it's just small domains such as other cities and small companies that cannot. Could it be that there is a bad cache entry in their routing tables or something? That fixed it with one of the people trying to send to us.Sorry for taking so long to get back, I needed some info before I could proceed on with this.Thanks.

Okay, I think I have something and it's as simple as a configuration change on the server, but I just don't know where.All incoming mail is routed through our Mail Filter appliance, and with the old Exchange 5.5 server we forwarded all outgoing mail through it as well. On the Exchange 2003 server it's being sent straight out to the internet, NOT going through the mail filter. So when it comes back in it hits the mail filter which is a different IP and DNS name and gets rejected. I'll post up some of what I am seeing so you may be able to verify what I'm thinking.mail.cityofholland.com --> exchange server --> MX priority 10 --> IP: 134.215.205.153mail2.cityofholland.com --> mxtreme mail filter --> MX priority 5 --> IP: 69.128.76.252-----Original Message-----From: Mail Delivery Subsystem [mailto:MAILER-DAEMON@domain.com]Sent: Sunday, March 02, 2008 10:32 AMTo: **********@domain.comSubject: Returned mail: permanent problems with the remote serverThe original message was received at Sun, 02 Mar 2008 10:31:50 -800----- The following addresses had permanent fatal errors ----- <*******@cityofholland.com>----- Transcript of session follows -----554 permanent problems with the remote server mail2.cityofholland.comSo do you think that my assumptions are correct?

I am going to answer my own question here just for the benefit of others if they happen to browse around and find this helpful. It was a DNS issue. However, it was not a DNS issue having to do with the MX or A records. We have a mail filter appliance and it had bad DNS settings so it was unable to verify domains unless it was specifically able to do a reverse lookup. So all in all, Make sure ALL your DNS is correct for EVERYWHERE.Hope this might help someone. We are all good now.