I've been using it for 2.5 years for my personal email (I don't do anything super complicated with email; mostly service notifications, the occasional correspondence with friends or recruiters or such). As far as UX, it's pretty mediocre (on both web and mobile) but it gets the job done for my purposes.

Hmm, I use it for everything, but I’m using the bridge with apple mail.app, maybe that’s a bit of the happy path for searching..

No real complaints besides the bridge sometimes pegging a cpu until I HUP it..

Apple mail app searching sucks. Might just be my personal experience but I find it easier to just search for email on gmail

It's not just you. Apple mail sucks for search.

I also use the bridge with Thunderbird with no problems.

Was literally about to posit that as a solution.

It’s way above my pay grade but I wonder if homomorphic encryption could be leveraged at scale without compromising security.

I've been using protonmail as my mail email service for probably close to 6 years. Earlier iterations of the UI were obviously basic but it's perfectly functional now and works very well and certainly not for "occasional use". The web client UI is great and has come on leaps and bounds particularly of late.

The mobile app has some way to go but more than adequate for daily use because I'm using it daily.