Creating Whitelists For Microsoft Internet Services
See: https://docs.microsoft.com/en-us/office365/enterprise/office-365-ip-web-serviceI've got a crude script that reads the resulting JSON and creates rancid scripts to load the objects and whitelist into the target firewall. I don't know how often this list is updated.(Sorry, this is more so I can find the link later.)
This is a collection of techical information, much of it learned the hard way. Consider it a lab book or a /info directory. I doubt much of it will be of use to anyone else.