Plesk has four login levels to provide you set control and appropriate responsibilities:
Adminstrator - Allows control for quick setup and management of all system items.
Client Control - Allow your support staff to create and administer domains from a single login.
Domain Owner - Allow your customer predeterminded permissions with a single domain administration.
Mail User - Set up individual mail accounts which gives each user a private interface to manage passwords, spam filters, anti-virus settings and much more.

Plesk is offered in 4 packages and you can choose Unix or Windows: