After long consideration, I have now moved email for all but my main domain (but that’s coming too) to Purelymail. Email without bullshit. And with the “Advanced billing mode” they really only charge by usage or $10 per year with the “Simple billing”, but even with Advanced that shouldn’t be much more than $1 per month for me.
What I like most is that there is no unnecessary limit on the number of users, aliases or custom domains. 👍
And to keep my emails even if Purelymail suddenly disappears, I set up a cronjob (based on this Dockerfile) that backs up my IMAP mailbox once an hour.