The SenderID filter incorrectly lets an e-mail message pass through Exchange Server 2003 when the DNS record does not exist (923346)

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Exchange Server 2003 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

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

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

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.

File name	File version	File size	Date	Time	Platform
Msgfilter.dll	6.5.7651.38	207,360	26-Jul-2006	16:44	x86

MORE INFORMATION

The SenderID verification process occurs as follows:

A sender sends an e-mail message to the receiver.
The receiver's incoming mail server receives the e-mail message and extracts the Purported Responsible Address (PRA).
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.
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