@nobodyinperson subject in the file name is going to seriously limit your options. I’d reconsider that requirement tbh

@nobodyinperson you’re already using mbsync. For all its drawbacks I don’t know of a better tool for what it does. Maildir’s design may seem odd but there are very good reasons for each facet. Possibly they aren’t of concern for your use-case (the three sub dir thing is for concurrent, lock-free writers relying only on POSIX semantics) but it isn’t a backup tool as such. I’m guessing you don’t run the mail server?

@nobodyinperson and iirc the hostname in the file name is a consequence of using the message-Id header, which is more likely to be unique than the subject, and also to use more predictable set of (safe) characters

@nobodyinperson a long time ago I used offlineimap, I don’t know if that’s advisable anymore. I started using mbsync recently (to use notmuch for searching) and I’ve already been frustrated by it. Seems to keel over if I delete a mailbox.