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