> Package html2text is obsolete!
It’s because I have an old version of mu and mu4e (https://emacs.stackexchange.com/questions/42343/package-html2text-is-obsolete). I’m on 0.9.18, which is the version that is in the Ubuntu 18.04 repos (https://launchpad.net/ubuntu/+source/maildir-utils), and hence what Mint 19.2 has. There doesn’t seem to be a PPA with a newer version.
It’s possibly an argument against using Mint for my personal desktop. I don’t need the stability that a server or office machine might need. I like Mint, I think it does a number of things well, but I may switch to Debian again for rolling releases (for example, in Debian Bullseye, mu4e is on 1.2.0 (https://packages.debian.org/testing/lisp/mu4es.debian.org/testing/lisp/mu4e)).