Question : Multiple Domain Mail Server

I am using Redhat ES 4.0 and never really got my arms around how to add multiple domains to a mail server.  I currently have 3 domains.  Do i use the virtusertable in /etc/mail or the domaintable in /etc/mail?  Mail is currently working or all 3 domains, however, the only issue I have is that each username i create would technically work for all 3 domains.  I need to have that separation of each.  Any thoughts would be appreciated.

Answer : Multiple Domain Mail Server

The linux user is "hr1" therefore the username in the email client is "hr1" not "hr". Remember email addresses and usernames don't have to match up, that's why you use the mailertable/genericstable