DocID: 1309 - What is a winmail.dat file?

What is a winmail.dat file?

Document ID: 1309
Last Reviewed: 4/22/2009

This document applies to:
MacLinkPlus Deluxe 16
MacLinkPlus Deluxe 15
MacLinkPlus Deluxe 14
MacLinkPlus Deluxe 10-13
Conversions Plus 6.6
Conversions Plus 6.054
Conversions Plus 4.0 to 6.001
MacLinkPlus 9.7 and below

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What is a winmail.dat file?


Sometimes emails are received with an attachment called "winmail.dat" that cannot be converted/decoded with MacLinkPlus or Conversions Plus (MacLinkPlus may recognize this file as a Comma Separated Value file). A winmail.dat file contains formatting code for an email sent by someone using Microsoft Outlook. It is caused by a setting in Outlook to compose emails in Rich Text message format, which works correctly if the recipient is also using Outlook.

However, if the email is sent to someone who is not using Outlook, a winmail.dat file appears as an attachment (it does not usually contain any useful information other than RTF formatting code). If the email also includes a regular attachment (like a Word or Excel file), that attachment may be included in the winmail.dat file, which MacLinkPlus and Conversions Plus cannot convert.


To receive the attachment correctly, the sender will need to change the message format to plain text or HTML. This can normally be done with the following steps from the Microsoft support site:

  1. On the Tools menu, click Options, and then click the Mail Format tab.
  2. In the Compose in this message format box, click Plain Text or HTML, and then click OK.

The following articles on the Microsoft support site have more information about winmail.dat files and message formatting in Outlook:

Winmail.dat attachments are included in received e-mail messages in Outlook

E-mail attachments are not visible to some recipients