Cna't send to certain domains

[dyeats]

On our recently installed Exchange 2003 server we cannot send to certain domains.
We get message stating:
"This is an automatically generated Delivery Status Notification.
THIS IS A WARNING MESSAGE ONLY.
YOU DO NOT NEED TO RESEND YOUR MESSAGE.
Delivery to the following recipients has been delayed."

Then we get a nondelivery report the next day stating:
"Your message did not reach some or all of the intended recipients.
Subject: RE:
Sent: 3/21/2005 9:34 AM

The following recipient(s) could not be reached:
John Smith on 3/22/2005 9:37 AM
Could not deliver the message in the time limit specified. Please retry or contact your administrator.
<servername.domain.com #4.4.7>

I thought it was a reverse DNS issue, and checked all that, and everything is OK. I have sent messages to a friend who returned the header to me and everything looks OK.

I think we may be getting blcked as SPAM, but cannot find us on any blacklists.

Anyone have any ideas?

 

[anawrocki]

There are some known firwall issues that can cause this, It has somthing to do with the size of the DNS UDP packets if memory serves correctly. It was funny because some domains would work fine while others would not. We ran into this with a PIX firewall but other firewalls can have the same issue. It can be fixed either at the firwall or a tweak on your DNS server depending upon your scenario.

 

[anawrocki]

Found my notes. Check this link. We used method #2 but either should work.

http://support.microsoft.com/default.aspx?scid=kb;en-us;828263

 

[dyeats]

This looks like a good possibility.

My firewall has no setting for DNS packet size, so I will also need to try Method #2.

Do I do this at the Exchange Server, or at my internal DNS servers that my Exchange Server points to?

Thanks for the help.

 

[anawrocki]

The DNS Server, it will change the method that it uses to make DNS requests. This only applies if your DNS server is Windows 2003. The issue does not exist as far as I know on Windows 2000 or earlier.

On the firewall it would be a UDP setting of some sort.