I'm going to plug fastmail. Rationale:

(1) tech support that actually reads your messages and replies with a solution demonstrating comprehension of the message that you wrote. Amazing. I've emailed them twice and gotten a great response both times.

(2) it is the best UI I've seen outside gmail;

(3) They have continued actively developing their UI, with nice updates released perhaps in the last 6 weeks.

(4) keyboard shortcuts that work

(5) Instead of inbox 0, I practice inbox 50k and it handles it fine.

(6) I just had a decade-anniversary there and I've never regretted it.

(1) tech support that actually reads your messages and replies with a solution demonstrating comprehension of the message that you wrote. Amazing. I've emailed them twice and gotten a great response both times.

Tech support forwarded an inquiry I was asking about an IMAP command in my MUA which led to an actual engineer that said my MUA was using an outdated/deprecated part of the IMAP protocol and provided the RFC for the new way of doing things, which then lead to a patch in said MUA. Very few companies offer this calibre of support, the only other one I can think of is Tarsnap.

(2) it is the best UI I've seen outside gmail

I think it's a much better UI overall than gmail; at least I found with gmail you had to manually paginate things, I can easily do a search in FM that might have 10000 emails over 20 years and I can usually jump to a specific month/year very quickly via scroll and then from there a specific day.

(5) Instead of inbox 0, I practice inbox 50k and it handles it fine.

Similar, 37k in my Inbox, nay issue. I have probably 200k overall across different folders. But I know I'm outsourcing a service, so I do full infrequent backups via IMAP.

Here's my (7):

Fastmail has the only web interface I've come across that handles (catch-all) aliases correctly and knows how to respond with the correct one every single time. Maybe roundcube/squirrelmail can do this, but roundcube/squirrelmail overall is not very good.

> (2) it is the best UI I've seen outside gmail;

I'd say it's better (maybe gmail has features it doesn't, but fastmail does everything I need and loads much much faster than gmail)

I think I'm over 20 years using Fastmail now? It just works. I've never had a single ounce of trouble with them. Their support is great. There are few products in life that I would recommend without question, and Fastmail is one of those. If only every company was this good.

Also a happy fastmail customer for the last several years.

Came here to say this. I've been with Fastmail a similar length of time and it just keeps getting better.