Mac Users Getting WinMail.dat Files instead of a PDF? Here’s the Fix.

A client using Office 365 recently contacted us with a problem that’s likely happened to you: you send a PDF attachment to a Mac user and they complain that the attachment is a WinMail.dat file they cannot view. Sound familiar? Here’s the fix:

1. Make sure the person you’re emailing is an existing contact in Office 365.
2. Use Powershell and run the following command:
3. Set-MailContact youremailcontact@example.com -UseMapiRichTextFormat Never
4. Send a test attachment to your contact.
5. The solution worked perfectly for our client. We hope it helps you out, too.