Configuring preferences and options in Outlook.com
I have the same problem. I have to re-install on my Pixel Android regularly (weekly). A real pain! Storage stays OK for a few days then suddenly blows up to 12-13GB. Re-installing does not go well either. I install as IMAP (GMX) (POP3 works but that's not what I want) and it takes about 10 tries, always saying incorrect userid or password. Eventually, it gets through.
I have been using my mobile for over a year without any issues until about a month ago. This can't be right. Is it an OUTLOOK bug? Or is it Android?