An update is available that changes the format of SMTP messages from TNEF to S-TNEF (841756)

MORE INFORMATION

By default, Exchange 2000 Server encodes outgoing SMTP messages that travel across a Routing Group connector in TNEF format. TNEF uses Base64 encoding. Base64 message encoding expansion can add approximately 33 percent to the message size.

When you send an e-mail message that contains an attachment across an Exchange 2000 Server Routing Group connector, you may receive a non-delivery report (NDR) that contains the following error message:

The message was not delivered because it is larger than the current system limit. Create a shorter message body or remove attachments and try sending it again.

The message encoding expansion that is associated with the Base64 format causes you to receive the NDR. You receive the NDR although the e-mail message is smaller than the current system limit.

Software update information

A supported feature that modifies the product's default behavior is now available from Microsoft, but it is only intended to modify the behavior that this article describes. Apply it only to systems that specifically require it. This feature may receive additional testing. Therefore, if the system is not severely affected by the lack of this feature, we recommend that you wait for the next Microsoft Exchange 2000 Server service pack that contains this feature.

To obtain this feature immediately, contact Microsoft Product Support Services. 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

Prerequisites

This software update has the following prerequisites:

You must be running Exchange 2000 Server in native mode for this update to take effect.
You must be running Exchange 2000 Server Service Pack 3 (SP3). For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
301378 How to obtain the latest Exchange 2000 Server service pack
You must have the August 2004 Exchange 2000 Server post-SP3 update rollup installed. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
870540 Availability of the August 2004 Exchange 2000 Server post-Service Pack 3 update rollup

Restart requirement

You do not have to restart your computer after you apply this update. However, Exchange services and Microsoft Internet Information Services (IIS) services are automatically stopped and then restarted when you apply this update.

Software update replacement information

This software update does not replace any other updates.

File information

The English version of this update 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 tool in Control Panel.

    Date         Time   Version            Size    File name
   --------------------------------------------------------------
   15-Oct-2004  01:30  6.0.6617.15       413,696  Phatcat.dll

How to apply the update

You must apply this update to Exchange 2000 Server mailbox servers and to Exchange 2000 Server bridgehead servers.

REFERENCES

For additional information about Base64 content transfer encoding, click the following article number to view the article in the Microsoft Knowledge Base:

323489 A description of Base64 MIME content transfer encoding

Base64 content-transfer encoding is discussed in Request for Comments (RFC) 2045. To review RFC 2045, visit the following Web site:

http://rfc.net/rfc2045.html

For additional information about the default IMAIL conversion process, click the following article numbers to view the articles in the Microsoft Knowledge Base:

259890 IMAIL conversion scenarios in Exchange 2000

326998 "Message not delivered because of current system limit" error message

For additional information about Microsoft software updates, click the following article number to view the article in the Microsoft Knowledge Base:

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