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 files[^1][^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.
microsoft.com
azure.com
bing.com
dynamics.com