Well, those messages did get sent via e-mail to other people watching the thread, so it was apparently possible to convert them to e-mail format just fine? I’d just like so I myself can have a copy of them too (and not just everybody else except me).
an MBOX doesn’t really make much sense,
Well, I beg to differ. MBOX is an well-supported industry standard for exchanging such “messages”, regardless of their origin.
I get very usable e-mails for RSS post, for various web forum posts (including Discourse!), for Usenet posts, for GitHub issues, for Fediverse posts etc. and I can archive them all in MBOX.
None of those are originally “e-mail” formats, but they all could be / were converted to it, and having them in such format does make sense and is very useful (at least for me, YMMV of course). You can see related post for list of reasons how/why it is very useful.
as it would be a contrivance (you’ll at least need to generate bogus email addresses).
Why would it need bogus email address? As I understand it, user_archive.csv contains my posts, and my email address (as well as my name) is available in preferences.json from that same archive.
But if for some reason it cannot use real email address (e.g. if it might contain other posts than just my own? PM maybe?), I’m fine with with bogus email addresses being used (e.g. claiming to be from Discourse username <noreply@localhost> or whatever).
No, I’d really prefer MBOX format (or Maildir, which I can easily convert to MBOX).
But if that does not exist, then yes – at the very least an easy way read those messages (especially offline, on Debian GNU/Linux system) would be nice too. Do you have any suggestions?