We have all run into the same frustration. Reaching out to someone whom we do not know or know particularly well, we are greeted by silence. An email or letter goes unanswered; a telephone call is not returned. So, we may try to contact the person again, often with the same result.
My rule was to answer everything--emails, letters, phone calls--within 48 hours. If I was out of town, my assistant responded that I would get back to the person when I returned. And I always did so as soon as I got back to the office.
Everything means everything. Even when I made a decision that produced an outpouring of negative responses (some virulently personal), I answered all of them--well, almost all of them, because unsigned letters obviously could not be answered.
The paradox a college president faces involves passion. You want everyone associated with the institution to feel strongly about it. Of course, when you make a decision that affects a group negatively, you will hear from members of that group. Often, what you hear will not be very pleasant.
Pay that price happily. When I heard from alums about a department I was eliminating or from neighbors enraged at the expansion of the college, I was happy they cared (fortunately, each of these issues only happened once). In truth, I would have preferred it if their passion would have been a bit less strongly displayed, but I nevertheless answered their calls, emails, and letters.
I used to say to my assistant my mother raised me "the right way." Answering something directed to you is nothing more than courtesy. Again, put yourself in the other person's position and think how you feel whenever an email, letter, or phone call is not given the courtesy of a reply. Then respond to it!