if I want to allow a client to add/edit/delete email accounts but not have access to any other parts of the Plesk Control Panel, how do I go about doing that???

 

The best you can do is create a new domain, go to "domain administrator" and remove all permissions you don't want them to have. They can then login with username "theirdomain.com" and the password specified above. You probably also want to view the "limits" section.