.TNEF File Extension

Transport Neutral Encapsulation Format

Developer Microsoft
3.7  |  3 Votes
Category Misc Files
Format N/A

What is a TNEF file?

File generated by Microsoft Exchange email programs such as Outlook; appears as an email attachment for email clients that don't recognize Microsoft's proprietary TNEF format; may cause the text "application/ms-tnef" to appear in the email if the email client does not recognize Microsoft Exchange formatting.

More Information

NOTE: Transport Neutral Encapsulation Format files with the extension ".tnef" are rare. Instead, unrecognized Exchange messages are usually seen with the filename Winmail.dat (.DAT file).

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Programs that open TNEF files

Included with OS
Updated July 8, 2011

Verified by FileInfo.com

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