This article was previously published under Q193118
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NOTE: These procedures only apply if you have installed Outlook with theCorporate Workgroup/Other option. This option allows you to use MessagingApplication Programming Interface (MAPI) services. To determine yourinstallation type, on the Help Menu click About Microsoft Outlook. In AboutMicrosoft Outlook you should see "Corporate" if you have the CorporateWorkgroup installation.
When you use Microsoft Outlook 98 to send e-mail containing attachmentsthrough the Internet, some recipients using e-mail clients other thanOutlook, report that the mail message includes an additional file calledWinmail.dat. The file is usually very small, but cannot be opened in themail message.
The Winmail.dat file is used to preserve formatting that the sending clientincludes in the message, but is not recognized by the receiving client. Inthe case of Outlook, the Winmail.dat file includes Rich Text Formatting(RTF) instructions. This type of formatting is used with the MicrosoftOutlook Rich Text Format and when using Microsoft Word as an e-mail editor.
To avoid including Winmail.dat, use the Plain Text mail format. To selectPlain Text for all messages, follow these steps:
On the Tools menu, click Options and then Mail Format.
In "Send in this message format", click to select Plain Text.
To send to certain recipients with RTF format and others with Plain Text,you must use the Personal Address Book. To set Plain Text by recipient,follow these steps:
On the Tools menu, click Address Book.
In Show Names From, select the Personal Address Book.
Select the addressee you wish to set as Plain Text and on the File menu, click Properties.
Click to clear the "Always send to this recipient in Microsoft Exchange Rich Text Format" check box.
For more information on Winmail.dat attachments, please see the followingarticle(s) in the Microsoft Knowledge Base:
149203XFOR: Preventing Winmail.dat From Being Sent Over IMC
138053XFOR: Preventing WINMAIL.DAT Sent to Internet Users