But you can't just say "if hostname == gmail.com", since it should also be done for any domain that uses Google Workspace for email.
You can't reliably say that a.b@ and ab@ are the same user except in a very small population (gmail.com) because you don't know how other domains will handle it.
Email is not a unique identifier which is how they're wanting to use it.
Badly worded on my part.