Microsoft KB Archive/185894

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The information in this article applies to:


 * Microsoft Outlook 98

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SYMPTOMS
Using Microsoft Outlook 98 you have enabled Transport Neutral Encapsulation Format (TNEF) to guard against information loss when sending mail. Because of this setting, recipients who do not use Outlook report that attachments do not display in mail they receive from you.

CAUSE
When TNEF is enabled, attachments are handled by this format. The Internet standards for encoding and attaching files such as Multipart Internet Mail Extensions (MIME) and UUENCODE are not invoked while TNEF is active, therefore e-mail clients that do not read TNEF in the message do not receive an attachment.

RESOLUTION
Enable TNEF only for recipients who are using Outlook or e-mail clients that are capable of interpreting TNEF. The Microsoft Outlook Rich Text Format enables TNEF for messaging in Outlook.

Internet Mail Only Installation (IMO)
To enable TNEF using RTF in each mail message that will contain Outlook items as attachments, follow these steps:


 * 1) On the File menu click New and then Mail Message.
 * 2) On the File menu of the blank message, click Properties. Click "Send in Microsoft Outlook Rich Text Format."
 * 3) On the Insert menu, click Items and then select the items you wish to include as attachments.

To enable TNEF in Outlook globally, follow these steps:


 * 1) On the Tools menu click Options and then click the Mail Format tab.
 * 2) In Send In This Message Format, click Microsoft Outlook Rich Text Format.

Corporate or Workgroup (CW)
Sending using Microsoft Exchange, Rich Text Format may be enabled globally or per recipient. The global procedure is the same as outlined for IMO installations above. To enable Exchange Rich Text Format per recipient, using either the Personal Address Book or Outlook Address book to create a mail message, follow these steps:


 * 1) On the File menu, point to New and click Mail Message. In the message, click to select an address from the list and click To.
 * 2) Right click the address and click "Add to Personal Address Book." Right click the address a second time, click Properties and then click "Always send messages in Microsoft Exchange rich text format.
 * 3) Send the mail message by clicking Send.

TNEF is helpful when sending Outlook items such as Contacts and Mail messages and other form based items. When not sending these items, TNEF should be disabled. In order to ensure that all users get file attachments as MIME items as expected set the mail format to Plain Text or HTML.

Rich Text Format (RTF)
RTF is a document type/message type that is used to define both the content of a message and how that message should look (with bold, colored fonts, etc). It was created by Microsoft to provide richly formatted messages before HTML was readily available for use with mail

Transport Neutral Encoding Format (TNEF)
TNEF is a method used to encode RTF so that it can be sent safely over the internet without losing data. TNEF is only used to encode RTF message types. This includes contacts, meeting requests, messages with voting buttons, etc. If an RTF message is not encoded before it is sent to the Internet, it will be converted to plain text. Most mail clients do not understand TNEF (or RTF for that matter). If a mail client receives TNEF that it doesn't understand, it will display a plain text version of the original message with an attachment called "winmail.dat" that can't be opened.

For more information on Transport Neutral Encapsulation Format (TNEF), please see the following articles in the Microsoft Knowledge Base:

Q185997 (IMO) TNEF Information Not Retained Sending HTML E-mail

Q186021 (CW) HTML Attributes Not Retained When Sending to MSN

Q186232 (CW) CC:Mail Does Not Preserve HTML Format Additional query words:

Keywords         : MsgRead Version          : WINDOWS: Platform         : WINDOWS Issue type       : kbbug Last Reviewed: July 28, 1999