If your Calendar users are having issues with invitations and RSVPs from Microsoft Outlook users, they might be caused by the Transport Neutral Encapsulation Format (TNEF). TNEF is a format that Outlook uses that can hinder Calendar from syncing these invitations correctly.
Identify an invitation sent with TNEF
A user can verify if an invitation is using the TNEF format in two ways:
- In Gmail, invitations from Outlook in the TNEF format have two attachments, whereas invitations using the standard iCalendar format have only one attachment.
- A more precise way to verify a TNEF-based invitation is to check the attachment name. If the Gmail message recipient clicks More
Show original, they should see a "winmail.dat" attachment if the invitation is TNEF-based.
Example:
Content - Disposition: attachment; filename="winmail.dat"
.
.
.
Content - Type: application/ms - tnef; name="winmail.dat"
To help invitations between Outlook and Google Calendar sync correctly, Google recommends that you turn off TNEF in Microsoft Exchange. This makes Outlook use a standard iCalendar (.ics) file format that works better with Google Calendar. For details on turning off TNEF, refer to your Microsoft documentation.
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