Comparing a few based on cheapest annual plan that includes custom email domains:

mailbox.org € 30.00 / $34.71

10GB+5GB storage, ample aliases, multiple domains, up to 10 family accounts

proton.me € 41.04 / $47.88

15GB storage, 1 account, 10 encrypted email addresses, 1 domain

fastmail.com € 51.44 / $60.00

60 GB storage, 1 account, multiple domains

For more accounts/users (e.g. Proton Unlimited or Fastmail Family), the pricing is reasonable. But mailbox.org certainly looks like the best value at first glance unless you need a lot of storage. If you've got 6 users and/or several domains, FastMail does look pretty nice.

It's been a few years since I went with Fastmail over Proton, but if I remember correctly Proton prioritizes privacy while Fastmail prioritizes other features which were higher up on my list, like storage (not as important to me now), custom domains, email aliases. Fastmail also gives you static webhosting, which I don't think Proton offers (could be wrong).

Proton apps are very janky in comparison. For example:

  You open Proton Mail.

  You'd like to read the second email in your inbox so you hit J a couple times.

  Nothing happens.

  J/K don't work unless an email is already selected so you use your mouse instead.

  You hit T to move the email to the trash.

  You'd like to read the next email so you hit J.

  Nothing happens.

  Hitting T didn't leave you with a selected email so J/K don't work.

I have anecdotally heard that proton has some more deliverability issues than Fastmail since it’s more preferred by scammers for its privacy features. That influenced my decision since I was probably already going to face some delivery challenges being on a custom domain.

I use and like proton for my custom domain. Haven’t used fast mail though so I can’t compare. I like that messages to other proton users are automatically encrypted.

I've used Fastmail for years but a year ago switched to Proton. For me the only reason to switch to Proton was that its hosted within the European continent, while Fastmail is hosted in

I would say that Fastmail is the "Ferrari of e-mail" services. It does everything well, or extremely well, especially if you have more advanced setups like wildcard domains.

In particularly, I miss being able to send from wildcard domains. While proton has a thing called simplelogin, it only works kind of seamlessly if you get an e-mail on a wildcard address and want to reply to that same address. Sending from any * domain requires you to make the address via the simplelogin page and isn't nearly as seamless. While you can make some sending addresses (i.e. regular aliases) in the protonmail interface, that's a trap, because once you've made an alias, you can't delete it unless there's no mail related to it in your mailbox anymore (even if you have a catch-all setup; I wonder if it has anything to do with how the encryption keys are setup, but it still sucks).

I also miss both snoozing and pinning mail. Officially, the proton mail apps (1) do support snoozing, but that requires "conversation view" to be enabled. I think the conversation view over groups e-mails too aggressively, and don't really understand why snoozing without conversation view isn't possible. It's utterly annoying. As far as I know, pinning e-mails isn't a thing in the proton apps. There are "stars" but these could have been labels (which also exist). They don't pin the e-mail to the top.

The proton mobile apps also lack various settings which are in the web interface, like access to sieves. The apps are sometimes a bit laggy, especially if you have a lot of e-mails, although there seem to have been some improvement on this end. I also still get double "fingerprint to unlock" requests sometimes.

Then there's theming, which I can imagine is (even) more of an opinion, but I liked the Fastmail interface more than the proton interface. I think its cleaner. Not a particular fan of any of the themes of protonmail.

I left Fastmail just as it added offline access. This was originally my biggest gripe. I might have stayed longer if they added it just before I left.

For Proton, they have been releasing a lot of new services lately. I hope they will spend a year or more, just polishing what they currently have. They did say they will spend some time on polish in a blogpost recently, but haven't really seen the fruits from this yet (or I care about different things than they do?). And I hope I will one day be able to add more domains to my account. Even with Visionary, you only get 6 domains for 6 users, and no way to add more.

I sincerely hope Proton will never add any of the AI nagging , the OP was talking about. If they do, I'll leave the instant.

(1) https://proton.me/support/snooze-emails