I currently have user accounts that have multiple aliases, for example:

Main: name@domain.com

Alias: alias1@domain.com, alias2@domain.com

Currently, I am able to use any of those 3 emails in the 'username' box during login, and it will log me into the email. Is there a way to setup so that email aliases cannot be used to sign on? I'd still be able to receive and send emails using those aliases in the main email account like it works now, except only the main email can be used to login.

Cheers!