[haxxorfreak]

AADInternals[0] is an excellent set of PowerShell modules for pentesting and performing recon against Azure AD as both an outsider[1] and for someone who has been invited to a tenant.

It has similar functionality integrated for discovering if a domain has an associated Azure AD Tenant and enumerating information about users in the tenant, who the "Owner" is and their contact information. As with many Microsoft products there are many configuration options and plenty of them aren't secure by default.

[0] https://o365blog.com/aadinternals/ [1] https://o365blog.com/post/just-looking/