PRB: "550 Quoted Name Does Not Match IP Address" SMTP Error Message (317099)

We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx

SYMPTOMS

When you send e-mail messages to remote Simple Mail Transfer Protocol (SMTP) servers, you may receive the following error message:

550 Quoted name does not match IP Address

On the local SMTP server that sent the e-mail message, a file that has the .rtr file name extension and that is associated with the e-mail message contains the following lines:

username@domainname.com
Remote connection was abruptly disconnected.

In a Network Monitor trace of this scenario, after the local SMTP server [sourceIP:3768] sends the EHLO command to the remote SMTP server [destinationIP:25], as follows

EHLO sourceFQDN

the remote SMTP server returns the following response to the local SMTP server:

550 Quoted name does not match IP Address

CAUSE

On public DNS servers, the A record for the source fully qualified domain name (FQDN) does not point to the source IP address that is owned by the source mail server.

This kind of problem typically occurs when Network Load Balancing (NLB) or the Microsoft Windows NT Load Balancing Service (WLBS) is involved. With NLB or WLBS, the FQDN is mapped to the virtual IP address that is used to implement load balancing. The remote SMTP server enables a feature to perform reverse DNS queries, and rejects the requests from the IP address that does not match the FQDN name that it claims. Therefore, the source FQDN of the virtual name does not match the real IP address of one node in the NLB or WLBS because it points to the virtual IP address of the NLB or WLBS.

RESOLUTION

To resolve this problem, use either of the following methods: