Multiple user accounts for same domain?

This seems like a real basic thing. It must be possible, but I can't figure it out.

I am the only user account "scott" on my domain example.com for my email that works fine at scott@example.com

Now I want my boss to have an account so he can get mail at charles@example.com

But when I create his account, I get:

Error
Domain already exists


Anybody know what I have to do to have multiple accounts for email at the same domain name?

Thanks!

I have the same problem.

how to add more than one user to the same domain to manage the domain

Does anyone know how to proceed, and if it is possible to make this configuration.

You guys really need to hire a professional to manage your servers!
@scottl31 Create a separate email account - that's all you need to do. So unbelievably simple.
@Victor Pinnola No, just no.