error c10308a2 // Error Creating/modifyng Emails Address from ADUC

Hello good afternoon, I have the following problem

I have a Exhange 2003 SP2, I install the system management tool on a workstation or a member server
I want a "Domain user" can create contacts in an OU, that "Domain user" belongs to a group that has permission to create users active directory in that same OU. Users are created without problem.
Now when it wants to create a contact, when you enter an address "smtp" it gives me the error:
Microsoft Active Directory - Exchange Extension
An Exchange Server could not be found in the domain.

Check if the Microsoft Exchange System Attendant service is running on the Exchange Server.
No ID: c10308a2
Microsoft Exchange Directory - Exchange Extension

That permits them I have to give the user, and as I do?

It is worth noting that the user has no other permissions on an object of exchange.

Also I say that because I was reading the KB of Microsoft and some pages of google without success.

Thank you very much