Well... you could always make a secure forum for admins only.
Have them enter their email address on the form so that it displays in the post.
Heck, if you wanted you could use one of the "Hide" hacks and put that in the template so that it hides the email address from everyone but those you specifically want to see it that can access that forum
Personally, I'd rather stick with the contact us form, but just giving you options to do what your considering
* Cyricx is the king of the secondary usergroup access system