Outside university business hours (typically 8:30-16:30), you can email email@example.com. This will reach staff who have volunteered to do what they can outside regular hours.
For emergencies that appear to demand immediate attention, such as water leaking near or in machine rooms and labs with computing equipment, call the Campus police at ext. 22222. They'll determine an appropriate action. They have a (small) list of staff phone numbers intended for problems that can't wait until the next business day.
Information about major network outages which prevent access to this page can be heard by calling the Computer Science Computing Facility (CSCF) Help Desk, ext. 31100.