docker – access mail from old dovecot server backup

I want to access a few gigabytes of old mail that I have in an archived copy of a dovecot mail server’s virtual mailbox files. I think it’s an old version of dovecot’s mdbox format? The server was built in 2008, and the archive taken in 2011. I’m guessing it might be mdbox 1.1.

I’m looking for suggestions of how to get this mail to the point where I can browse it with thunderbird.

It would be awesome if I could fire up an old version of dovecot to serve this mail via IMAP, possibly in a docker container. OR perhaps newer versions of dovecot can recognise the old format? Maybe a conversion tool of some sort?

Any help with identifying the format/version would be much appreciated. My files look like:

domain/
  username/
    dovecot.index
    dovecot.index.cache
    dovecot.index.log
    cur/
      1314076009.V55I369181M295175.mail.exmaple.com:2,STa
    new/
    tmp/
    .folder/
      dovecot.index
      dovecot.index.cache
      dovecot.index.log
      cur
      new
      tmp
    .folder.subfolder/
      dovecot.index
      dovecot.index.cache
      dovecot.index.log
      cur
      new
      tmp

There’s of course more folders, and more mail files, with flags in the file names as in the one that’s there for an example.