Mass e-mails can be a good way of communicating with students. But they can also be the cause of problems. This year at the University of Iowa, Students for Bush commandeered the entire campus address list to stump for its presidential candidate. Limiting unwanted intrusions while establishing policies concerning the appropriate use of e-mail can be a vexing responsibility. One of the most common approaches to the problem these days is the honor system. At Hamilton College, a college of approximately 1,700 in upstate New York, students are expected to know and follow policy guidelines: penalties are imposed for not following them.