Earlier quoted context omitted.
+1 for Migadu or ProtonMail, both offer great service, but Migadu with $19 yearly plan and amount of features is just incomparable to any other service.
Worth noting i suspect they had some issues and maybe the company was sold? It was quite young company. I had it for few years but there was very litle activity, no bug fixes, updates, messages. It was a bit worrysome. Now they have changed branding and pricing so hopefuly its moving again.
But I’m using them for few years and never been happier. :)