Gregory's Server@thunderbird just tried to migrate from k9, import from app did not work (file worked). There already is an older ticket on GitHub, but is it not assigned.
Next thing which is a huge show stopper for me is the missing support for nested and collapsible/expandable IMAP folders. The "folder.subfolder.subsubfolder.foo" workaround is a real deal-breaker, especially when you have 100 folders (incl subfolders). There also already is an existing unassigned ticket for this.
The rest seems fine so far 👍
@DaAnda Thanks for the feedback, and for making it both descriptive and honest. It's good to know what missing features potential users need most, and that can help us prioritize our roadmap.