Rated 5 out of 5 stars

@random randomofamber
1.download >image_zoom-0.4.6-fx+tb+sm.xpi<
2. extract only the >install.rdf< file with Winrar or Zip
3. open >install.rdf< with notepad
4. change :
<!-- Thunderbird -->
<em:targetApplication>
<Description>
<em:id>{3550f703-e582-4d05-9a08-453d09bdfdc6}</em:id>
<em:minVersion>2.0</em:minVersion>
<em:maxVersion>3.1.*</em:maxVersion>
to:
<!-- Thunderbird -->
<em:targetApplication>
<Description>
<em:id>{3550f703-e582-4d05-9a08-453d09bdfdc6}</em:id>
<em:minVersion>2.0</em:minVersion>
<em:maxVersion>6.1.*</em:maxVersion>

"you replace only 3.1.* with 6.1.*"
and save
5. add install.rdf to image_zoom-0.4.6-fx+tb+sm.xpi
6. install image_zoom-0.4.6-fx+tb+sm.xpi with thunderbird

This review is for a previous version of the add-on (0.4.6.1-signed.1-signed).