[scarface74]

When you use a federated login, you still can assign an email address to the federated user. Most of them will even pass one to you.

But, do you really want your users to have the added friction and probably just move on to another site, and do you really want the responsibility of providing your own authorization? I work for a B2B SASS company and we highly encourage users to use their company’s AD account that we federate with.