Rated 5 out of 5 stars

wonderful add-on on Thunderbird and this add-on works also on Postbox 3.0.11, you should only paste follow code into install.rdf file

<em:targetApplication>
<!-- Postbox -->
<Description>
<em:id>[email protected]</em:id>
<em:minVersion>3.0</em:minVersion>
<em:maxVersion>3.*</em:maxVersion>
</Description>
</em:targetApplication>

This review is for a previous version of the add-on (0.7.5).