Email back-up and long-term archiving
There's currently no decent solution for IMAP back up on Linux as fair as I'm aware, you get to choose from command line tools or... nothing? Geary's database doesn't currently serve as a backup, since if you lose all of your email on the server, there's no way to put it back. Also per #173 (closed) the current SQL format isn't friendly for host backup tools anyway, although that will get less worse as progress is made through #453.
So it would be good to have a plugin that serves these purposes - something that pulls mail off the server/out of the local database in a form that is suitable for backing up locally and provides a way of putting it back on the server in case of mail loss.
If this could integrate with Deja Dup, all the better.