The whole point of having "vanity domain" email addresses - for 20 years now! - has been to be easily migratable when something changes in the cloud. So I'll just do that again if purelymail doesn't work out. It's very cheap; I get the impression you're paying just enough for the sole proprietor to pay his AWS bills and be "ramen profitable". Who knows how long this will last.
Impression of the service with my other domain, whose MX records I've already switched, have been pretty good.
Note on the 20 years: Got the domain, ran completely on-premises email infrastructure for a few years, then switched to "Google Apps for your domain" when it became available.
A Privacy online guide curated by tech-savvy HNers would be a welcome birth to the world.
We NEED digital privacy. Full Stop.