office365.com messing up folders via IMAP, when they look ok with their web access

I’m trying to use an Office365 mail account via IMAP – as I don’t have access to usable MS Exchange client (or do I?); my mail client is BetterBird (~= Thunderbird + fixes) on Linux.

I’m facing problems with my folder hierarchy:

  • I’m seeing gray “Tombstone” folders, where actual folders used to exist, that I moved elsewhere.
  • I don’t see some of the folders I actually had moved (and may coincide with the tombstones)
  • Deletion of some folders, especially tombstones, is impossible.
  • Can’t really clear the trash – it seems to fill up again after I restart Thunderbird, or even earlier

on the other hand – if I use MS’ web interface, all folders look just fine and respond nicely to whatever it is I try to do with them.

My questions:

  • Is the problem with MS’ IMAP support or with Thunderbird’s IMAP protocol handling?
  • Is there something I can do to make the folders behave nicely, other than not-using-IMAP?