This list doesn’t include all @Microsoft properties, just second-level domains that load on HTTPS, plus microsoftonline.com
and windows.net
, which load on HTTPS with some subdomains only.
I collected them by combining two Office configuration files1, 2 and regexing the domains only, then keeping only the second-level domains that didn’t fail on HTTPS.
These are in alphabetical order except the first entry, whence @1Password supplies its rich icon.
https://microsoft.com
https://azure.com
https://bing.com
https://dynamics.com