To impersonate a Domain Administrator, log on using an Administrator Account and go to Anti-Spam Engine > Domain Policies. Click on the Edit/Pencil icon to the right of the domain you would like to configure.
In the pop-up window, scroll down to Domain Administrators. If no Domain Administrator is listed here, you can add yourself or another user by entering an email address and saving the record.
Once a Domain Administrator has been added, you can impersonate that Domain Administrator by clicking on the Impersonate icon as shown below.
To impersonate individual users, you can go to Anti-Spam Engine > User Policies. Beside each individual user, there is an Impersonate icon as shown below. Clicking on the appropriate icon will allow you to impersonate that user.