Installing with TB 7.0 (@ Andy) Rated 5 out of 5 stars

Then, try with 7.0 instead of 7.* (again, making sure you're editing the correct <em:maxVersion> value for TB, not SeaMonkey or SpiceBird). Have you removed your old version of Lookout and downloaded a fresh XPI file from this site before installing the modified package? I have used this trick for my own build of Thunderbird (7.0.1) and it does work on my side. Hope it helps.

This review is for a previous version of the add-on (1.2.12).  This user has a previous review of this add-on.

awaiting review

The compatible version has been awaiting review.