Confirmed by looking at the thunderbird.desktop file in thunderbird 3.0.3+nobinonly-0ubuntu1 sourcecode. I believe this could be fixed by adding the "Mail" category to Thunderbird's .desktop file.
Confirmed by looking at the thunderbird.desktop file in thunderbird 3.0.3+nobinonly -0ubuntu1 sourcecode.
I believe this could be fixed by adding the "Mail" category to Thunderbird's .desktop file.