preventing users from logging into wrong domains
So far, I have yet to find a way of preventing users from logging into the server using any domain name which exists on the server.
Is there a way to enforce users to log in using the domain name they were assigned?
Right now, firstname.lastname@example.org can log in from url host.domain3.com for example. I want to force email@example.com to only be able to log into their account at firstname.lastname@example.org.