Rated 1 out of 5 stars

Lesson 1 for developers: How to lose your user base and collect 1-star reviews: Start making payment compulsory. Instant success!

I had previously donated to this add-on but this is an instant removal. I only used this add-on for a few features in the end anyway.

Not so "Smart" move of the developer, there are many other ways...

This review is for a previous version of the add-on (2.2.2). 

... or you could have asked for a free license. Maybe the Add-on wasn't for you, after all, there are alternatives. I still hope your employer pays you something for your work.

I had to make a choice to either give up my day job and keep working on the Add-ons fulltime to keep them up to date with the crazy changes that Mozilla is pushing down or walk away and and leave my user base unsupported. This would mean SmartTemplate would stop working from end of August. I had thought (and tried) any other ways and you will see soon how many free (as in beer) Add-ons will stop working once Thunderbird 68 is released.

Necessary changes, just to make sure it keeps working for ESR 2019 / 2020:

I answered 100s of support emails, helped people with their HTML / CSS problems and implemented new features to solve their problems, completely pro bono.

I still know that Monetizing ST⁴ was the correct way forward, but asking for voluntary donations / only have Pro License users finance this work was not the correct way. Also, a payment of 45cent/month for that work is not unreasonable; but you will not get anything even from the most generous user if you do not ask - donations were an absolute exception. Most people believe we are paid by Mozilla or some other big corporation that has "spare cash" - this is not the case.

If you don't want to ask for a free license, I would recommend using the quicktext Add-on instead.