You don't even have to personally, many email providers were blocked by Microsoft for no apparent reason. We lost critical emails because Microsoft decided one day that alerts from one of our companies was mass spam and started blocking them, after getting their emails daily for 5+ years.

That is one of the ways how Microsoft acts evil. Email was never supposed to be this way. You have zero visibility into why some emails are blocked. One thing is to quarantine emails / put them into spam. But to reject them without any proper technical reason (like wrong SPF) is a nightmare from sysadmin standpoint.