Shout out to office365 for being a piece of crap when it comes to IMAP.

If you launch something like fetchmail or imapsync at it, it will close the connection in the middle of the sync because you're doing something nasty in his opinion.

Last time I switched jobs and had to download 18+ GB of emails it took me days to download them all off office 365, and I was to run it in a while true loop in screen. Luckily I didn't wait for the last day to start downloading my emails.