You can send a Transport Neutral Encapsulation Format message to an external contact through Exchange 2000 when the contact is included in a distribution group

You can send a Transport Neutral Encapsulation Format (TNEF) message that contains attachments to an external contact through Microsoft Exchange 2000 Server. This problem occurs when all the following conditions are true:

1. You create a mail-enabled contact for a user who does not receive mail through Microsoft Exchange. For example, you create a mail-enabled contact for user@hotmail.com.
2. You create a distribution group. Then, you add the external contact that you created in step 1 to the distribution group.
3. You set the distribution group expansion to an Exchange expansion server.
4. You use Microsoft Outlook to send a message that contains attachments to the distribution group that you created in step 2.

TNEF is a Microsoft proprietary method that is used to encode Rich Text Format (RTF) messages that are sent across the Internet. Some e-mail clients do not understand TNEF encoding. Therefore, TNEF should be used only if you are sure that a TNEF message will be received by recipients who use Outlook, Microsoft Windows Messaging, or Microsoft Exchange Client.

If an e-mail client does not understand TNEF, the e-mail client may incorrectly determine that a TNEF message is damaged. By default, Exchange 2000 should not allow TNEF messages to be sent to external e-mail addresses.

Cumulative update information

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

Hotfix information

A supported hotfix is 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.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if 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. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language. 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 tool in Control Panel.

For more information about TNEF, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in Microsoft Exchange 2000 Server.