I always had this policy when I was teaching college classes.<p>Obviously, the rule didn't apply to personal problems (grade worries, student (or family) illness), but if I got a generic question about an assignment in email, I'd ask the student to repost it in the online forum for the class.<p>It worked very well -- it's a rare assignment question that only one student is wondering about (whether they actually ask or not). It cut down on the number of emails I had to answer, saved time for the other students (they were supposed to check the forum before asking questions), and gave me a central location to check when I was prepping/improving the course for the next semester (rather than being buried in the Satanic depths of my email box, all of the questions and clarifications for that particular course were collected in one spot).