Rated 5 out of 5 stars

Doesn't work on TB 17.0.6 too, but I suppose this bug it's not strictly related with TB version.
After a few testing I saw that the addin doesn't manage the winmail.dat attachment because of a missing entry into mimeTypes.rdf file.

To fix it:
- close all Thunderbird instances
- open your profile folder (on Windows press WIN+R, write %appdata% and press ENTER)
- make a backup copy of mimeTypes.rdf file
- open mimeTypes.rdf with your preferred text editor
- go to the end and paste this content ust before the last line (</RDF:RDF>)
----
<RDF:Description RDF:about="urn:mimetype:application/ms-tnef"
NC:fileExtensions="dat"
NC:description=""
NC:value="application/ms-tnef"
NC:editable="true">
<NC:handlerProp RDF:resource="urn:mimetype:handler:application/ms-tnef"/>
</RDF:Description>
------

Mail sent to developer.

Rated 3 out of 5 stars

Not working here on TB 17.0.3.

Installed on 20+ PCs, both Windows XP and Windows 7 (x64) but none of them worked, still see only one winmail.dat attachment.

No way to file a bug on mozdev.org..., I'll send a mail to developer.