making pop and smtp work with accounts

[Tyler Littlefield]

Hello list,
I've got a quick question;
I want to be able to make pop and smtp work with accounts.
I have it configured, but I need a username and password in order to access it. I'm not sure how to add smtp users, or if there even is such thing.
Is there a way to make exim4 and courier use shell accounts for mail, or do they have their own type of account.

Thanks,
Tyler Littlefield
Web: tysdomain.com
email: tyler at tysdomain.com
My programs don't have bugs, they're called randomly added features.