Rated 5 out of 5 stars

Is it because this is still in EXPERIMENTAL status that it is not being updated automatically in Thunderbird?

This review is for a previous version of the add-on (0.4.7).  This user has other reviews of this add-on.

The Add-ons in the sandbox(EXPERIMENTAL) is not being updated automatically.
I will nominate this add-on for become public with next version.

Best Regards,