I found Tuta to be lacking.
Conversation view is incomplete https://github.com/tutao/tutanota/issues/6 - https://github.com/tutao/tutanota/issues/5051
“when you have multiple addresses and custom domains getting hundreds of emails… it takes forever for the emails to load” https://community.centminmod.com/threads/skiff-email.24363/
Search isn’t working in firefox “your browser doesn’t support data storage”. As the search index needs to be stored in your browser, it does not work in private mode/incognito mode.
Free accounts get deleted if you do not log in for six months.
How about a basic Squarespace business website?
I looked at a bunch of options before and Wordpress seemed like one of the most promising: https://lemmy.world/post/12989654