James today provides a command line tool to do administration tasks like creating a domain, listing users, setting quota, etc.
It requires access to JMX port and even if lot of admins are confortable with such tools, to make our user base broader, we probably should expose the same commands in Rest and provide a fancy default web ui.
The task would need some basic skills on frontend tools to design an administration board, knowledge on what REST mean and enough Java understanding to add commands to existing Rest backend.
In the team, we have a strong focus on test (who want a mail server that is not tested enough ?) so we will explain and/or teach the student how to have the right test coverage of the features using modern tools like Cucumber, Selenium, rest-assured, etc.