The ability to see up sieve filtering is great too. I’ve got a massive script that automatically sorts and files away most of my emails.
I want to like Proton Mail, but their sieve filtering kind of sucks, and with large mailboxes it slows down to an almost unusable amount.
A lot of the mods for big providers like FB require counseling after the horrible crap they see (not just CSAM, but also terrible things like animal abuse and mutilation, etc). Unfortunately, the big companies have outsourced much of it to other countries where there aren’t as many worker protections, traumatizing people and replacing them when they can’t meet some arbitrary metric.