Rated 5 out of 5 stars

I was also longing for a Thunderbird version so I tried hacking install.rdf - and guess what, it worked.

The same way you fake maxVersion for abandoned add-ons, you can also add Thunderbird as a targetApplication.

Here's what you need to add into install.rdf next to Firefox targetApplication:

<em:targetApplication>
<Description>
<em:id>{3550f703-e582-4d05-9a08-453d09bdfdc6}</em:id>
<em:minVersion>3.0</em:minVersion>
<em:maxVersion>3.1.*</em:maxVersion>
</Description>
</em:targetApplication>

This review is for a previous version of the add-on (0.2.20100210).