I have their legacy "professional" plan, and the reason it's so expensive is because back then, you could pay to add additional custom domains.

I believe they now removed that feature? I cannot find it anywhere.

Basically I have a bunch of custom domains for personal stuff, work stuff, small home business stuff, etc, and I use ProtonMail to consolidate it all into one inbox.

So while ProtonMail has a bunch of pros, and you'll be able to find them easily, I think it could be more beneficial to tell you about what I would consider cons.

Like what's happening now, they always roll out features to their top tier plans first, which can definitely suck. They absolutely don't care about how much people pay them, they care about the random plan badge associated with the account instead. When they finally added the ability to search for your emails, they rolled it out to visionary members first. Quite insane to have something so basic be locked behind a top tier membership for a limited time.

In my couple years being with them, they've had a few times where their services crapped the bed for multiple days straight. If I remember correctly, last year their mail and calendar services went down on a Monday and took until Wednesday for them to be fully restored. Absolutely destroyed productivity when you are unable to message your clients or check your calendar.

Proton also makes big claims and almost never meets them. They promised a redesign of the Android app for a couple years, and when it finally came, they were over 1 year past their already extended date. The same thing is happening with the new rewrite of the Android app that is supposed to support basic mail features like email threads.

Overall I like their services. The web UI is clean and has super awesome features like keyboard shortcuts to easily manage your email. Their services haven't went down at all, or at least not significantly to my knowledge in 2023 yet, which is good. If you're ignorant, and you don't keep up to date about their new features or planned features, you'll be happy. You really only start to get frustrated when you're waiting for a basic feature and hear it's limited to a higher tier at the moment.

You also have to be okay using their mobile app, as third party mobile email clients don't work. On desktop a few different ones will work, like Thunderbird, but only if you use proton bridge with it.