...and microsoftonline.com is not among them (unlike microsoftonline.net and other variants). But it seems to have been registered in 2002, and the record looks legit:
https://whois.domaintools.com/microsoftonline.com
https://github.com/HotCakeX/MicrosoftDomains/blob/main/Micro...
but that one doesn't contain any microsoftonline.
...and microsoftonline.com is not among them (unlike microsoftonline.net and other variants). But it seems to have been registered in 2002, and the record looks legit:
https://whois.domaintools.com/microsoftonline.com