How to edit user permissions

[aadesh170]

I want to know that it is possible to change the permissions of Domian Administrator like we create a domain administrator user type user xyz@pqr.com and i want to give permission to that user only to see their emails i.e. xyz@pqr.com, It can see only email subjects of other host names which have pqr.com domain.It cannot see the emails of other host names except their own emails but it can see the subjects of emials of other hostnames

Thankyou