Posted almost 2 years ago. Visible to the public.

When attachments and calendar invites appear as winmail.dat

When an incoming e-mail contains a single attachment named winmail.dat, a Windows user has misconfigured their Outlook client. They are probably trying to send you an attachment or calendar invite, which are now compressed into the winmail.dat attachment using a proprietary format. Outlook will also attach a winmail.dat if such an user wrote a formatted e-mail.

Ask the sender to fix their Outlook

If possible, ask the sender to fix their Outlook configuration:

Gmail might work

Gmail can often decode winmail.dat files and show the contained events and attachments.

If you are not using Gmail, consider forwarding the e-mail to a temporary Gmail account for this.

tnef doesn't work

There is an Ubuntu package called tnef Archive that claims to extract winmail.dat files, but it never worked for me. It just exits silently without doing anything.

Last resort: Use a Windows VM

Install a Windows VM with Outlook.

Owner of this card:

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Henning Koch
Last edit:
almost 2 years ago
by Henning Koch
Posted by Henning Koch to makandra orga
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