Rated 5 out of 5 stars
Essential backup in order to make your emails look professional. Covers pretty much all situations and the author is going the extra mile supporting and improving his addon. Pro license highly recommended!
As long as the author still supports version 60 of TB I'll keep being a loyal user. Can't move away from v60 because they in their glorious wisdom decided to remove full theming support in later versions. Another topic...
I will try to keep support Thunderbird 60 as long as possible! In fact, I had a Postbox user complaining about incompatibility so I had to take down the compatibility flags on the variable page for 2.1 onwards - 2.9.2 will be "mostly" compatible with Postbox 5.5 (I haven't looked at the file template button integration yet). There is a github issue [#55] with some hot-patched versions for Postbox users