Yes, you can manage access to the web interface for individual e-mail recipients (e-mail users) under "Web interface users > Manage e-mail users". They can log into the system administration with their e-mail and password and manage their own settings. Adding and removing email users does not affect current email processing; this page is only used to manage individual accesses to the interface.
How can I restrict the rights of a user?
Under "Webinterface users > Manage permissions" you can define which menu items are to be available to an e-mail user. Each menu item can be accessed via 4 possible HTTP methods.