Microsoft KB Archive/923346

= The SenderID filter incorrectly lets an e-mail message pass through Exchange Server 2003 when the DNS record does not exist =

Article ID: 923346

Article Last Modified on 10/25/2007

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APPLIES TO


 * Microsoft Exchange Server 2003 Standard Edition
 * Microsoft Exchange Server 2003 Enterprise Edition

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SYMPTOMS
The SenderID filter tries to look up a domain name system (DNS) record that does not exist for an incoming e-mail message in Microsoft Exchange Server 2003. When this occurs, the SenderID filter incorrectly lets the message pass through Exchange Server 2003.



CAUSE
This problem occurs because the SenderID filter incorrectly assigns TempError status to the message when the DNS record does not exist.



Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
You must have Microsoft Exchange Server 2003 Service Pack 2 installed to apply this hotfix.

Restart requirement
You do not have to restart the computer after you apply this hotfix. The Microsoft Internet Information Services (IIS) Admin Service and all dependent services are stopped and then restarted after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfix.

File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
The SenderID verification process occurs as follows:
 * 1) A sender sends an e-mail message to the receiver.
 * 2) The receiver's incoming mail server receives the e-mail message and extracts the Purported Responsible Address (PRA).
 * 3) The incoming mail server verifies which domain claims to have sent the message. Then, the incoming server examines the DNS for the sender policy framework (SPF) record of that domain.

Note SPF records identify authorized outgoing e-mail servers.

The incoming server determines whether the sending e-mail server's IP address matches any of the IP addresses that are published in the SPF record.
 * 1) If the IP address matches an IP address in the SPF record, the e-mail message is authenticated and delivered to the receiver.

If the IP address does not match an IP address in the SPF record, the e-mail message fails authentication and is not delivered.

Based on the evaluation of the SenderID record, every message is stamped with a SenderID status. If the DNS record does not exist, the SPF record for the domain should continue to be processed.

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

817903 New naming schema for Exchange Server software update packages

Additional query words: anti-spam Ex2003

Keywords: kbemail kbreceivemail kbhotfixserver kbqfe kbfix kbbug kbpubtypekc KB923346

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