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MS Outlook for Mac does not open winmail.dat files.

Anonymous
2024-03-25T08:42:05+00:00

Hi,

A contact uses Outlook for PC.. I use Outlook for Mac version 16.83.

My business contact sends me e-mails. I can read the body, but cannot open the attachments. The attachments are all called win mail.dat.

I've found on forums that Apple-mailprograms use the RTF format and Microsoft-mailoprograms use the TNEF format, and that this causes files to become unreadable when sent from a Microsoft mailprogram to an Apple mailprogram. The most common advice is for the sender (Microsoft user) to adjust his settings. However, in my case, both users have Microsoft's Outlook: one for the PC and the other for Mac.

In any case, my contact does not wish to adjust his settings from TNEF to HTML, as he fears this will make other unwanted changes to his messages to other recipients.

I am surprised that two Outlook products (one for PC, one for Mac) are not synchronised as a result of which I cannot open files.

How do I adjust my product (Outlook for Mac) so that I can open these attachments? Converting these files one-by-one in an external online tool is not a solution (doesn't work and would not be efficient).

Thanks.

Olivier

Outlook | MacOS | Legacy Outlook for Mac | For business

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  1. Anonymous
    2024-06-04T08:50:03+00:00

    Hi Oliver:

    I also cannot open .dat files on Outlook for Mac. I CAN open the .dat files on my iPhone using the Outlook application. Not sure why that works but it does.

    Thanks

    Robin

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  2. Anonymous
    2024-03-25T09:51:25+00:00

    Hi Shannah,

    Thanks for your quick reply.

    When in Outlook for Mac, I save the attachment in a folder, then I still can't open it.

    How do I assign the correct app to open it?

    Thanks again.

    Olivier

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  3. Anonymous
    2024-03-25T09:34:54+00:00

    Hi Olivier

    Thank you for reaching out.

    Sadly the only option is to Save it to your desktop using your email client's save attachments facility — in Apple Mail, you can right-click the attachment and choose Save. In a web browser, navigate to Open winmail.dat attachments.. Click Choose File and navigate to the attachment you saved.

    This is a restriction via Apple and not Microsoft. As you know Apple products have varying limitations within the Microsoft software.

    DAT is a generic data file, and the data it contains could be just about anything, from text and graphics to images and even video. This creates a challenge with opening it, since if macOS can't tell what kind of data the file holds, it can't assign the correct app to open it.

    Regards,

    Shannah

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