https://github.com/HotCakeX/MicrosoftDomains

...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

but microsoftgenuinerewardsrc.com is! shameful!