Last Updated: 2021-05-16
I used protonmail for a new project, established the address over a few months, then realized, when I wanted to send my first newsletter to my 500 or so subscribers, that protonmail has strict daily limits (like 300 per day) and 50 per hour. I had to backtrack and create a Gmail email instead.
I could have avoided this problem by laying out the quantitative requirements beforehand and checking whether each provider met them. This applies broadly, to any "buy-in" solutions.