If you leave the University without graduating, your email account, network access, and email forwarding will be deactivated a year after the beginning of your last registered semester. Students on an approved leave of absence from their college or academic department can be reactivated at the request of their department. 

What counts as "registered"?

To be considered registered at the University of Illinois at Urbana-Champaign, you must register for at least one class through the Banner Enterprise Self-Registration tool. You can register for zero credit hours and still be considered a registered student. If you're a graduate student pursuing an advanced degree and have chosen not to register for a semester, you may be eligible for continued email and network services if sponsored by your department.  You will need to request sponsorship from your advisor (or someone of authority in your department) stating your need for continued services and for how long.