Microsoft KB Archive/150969

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Article ID: 150969

Article Last Modified on 10/28/2006


  • Microsoft Exchange Server 4.0 Standard Edition

This article was previously published under Q150969


When you use the Microsoft Exchange Internet Mail Connector (IMC) to send SMTP mail the IMC may try to send messages to itself. When this happens, users will receive non-delivery reports (NDRs).


The following is an NDR that a user might receive:

FROM: System Administrator [postmaster@Org.Site.Com]
DATE: Monday, May 13, 1996 9:29 AM
TO: Test User
SUBJECT: Undeliverable:

Your message did not reach some or all of the intended recipients.

Subject: Subject of message
Sent: 5/13/96 9:29:16 AM

The following recipients(s) could not be reached: on 5/13/96 9:29:16 AM
Recipient Not Found

This problem occurs if the IMC is using DNS for the host name resolution. When the IMC attempts to resolve a host, it will attempt to query the DNS server for the host's IP address. If a site uses an MX wildcard record, it will direct all mail to that site. This could mean that the IMC will try to send mail to it's own IP address. The following scenario could help explain this:

The computer running the IMC is located in the domain and there's an MX wildcard record of * in the DNS.

The IMC will add to any address except ones ending in Any address that ends in will use the address expressed through the MX wildcard record.

Since every address the Microsoft Exchange Message Transfer Agent (MTA) tries to resolve will end in, all mail will go to the same Microsoft Exchange Server. This may be the Microsoft Exchange Server that the IMC is running on.


If you are experiencing this problem with the IMC, you can add a registry value to prevent it. The registry key is:


From the Registry Editor menu, click on Edit, then the Add Value option from there.

   Value Name: DisableResolverSearchList
   Data Type: REG_DWORD
   Value: 1 (or any non-zero value)

This is case sensitive and should be typed exactly as show above. You will need to restart the IMC for the registry key to take effect. Then you can use Restest.exe to see if it worked. This utility can be found on the Microsoft Exchange Server CD-ROM in the Support\Utils\I386 directory.

Additional query words: loop looping resolve

Keywords: kbusage KB150969