O365 is the most unreliable, haphazard, glued together, frequently unavailable piece of $&,$/$! that my team and I have used for 4 years. I can honestly say that I have never in my life experienced such repeatedly unreliable software in my life. Worse yet it's backed by the most incapable off-shored and overworked support team(s) that we now no longer bother to log queries with.