tnef-filter automatically converts TNEF attachments in an email to MIME format. It's designed for automated use with a Mail Delivery Agent such as procmail or maildrop.

For the benefit of search engines, TNEF attachments are typically named winmail.dat.

Use a recipe like this in your .procmailrc file:

:0 fw
* ^X-MS-TNEF-Correlator:
| /path/to/tnef-filter

As rewriting the emails can break things like DKIM signatures, you might want to write the original emails to a file for backup purposes:

:0 cw :
* ^X-MS-TNEF-Correlator:
| gzip >> tnef.gz

:0 afw
| /path/to/tnef-filter --purge

By default tnef-filter will keep the original TNEF attachment, as it doesn't convert all the information held within it. If you're not worried about data loss, or have kept a copy of the original email, the --purge flag can be used to override this behaviour and remove the TNEF attachment.

• Perl 5
• Convert::TNEF
• File::MMagic
• MIME::Tools

tnef-filter is available under the terms of the ISC license, which is similar to the 2-clause BSD license. See the LICENSE file for the copyright information and licensing terms.