When addressing academic departmental assistants via email, should I use their first name or just Mr./Ms. X? It seems very common for them to normally prefer being addressed by their first names (since Mr./Ms. seems to be very rarely used in Academia).
My policy : the first time you contact the person, go with Mr. Doe (or Ms. Doe), but sign with your first name. The latter is a signal that you are OK with a "first name email relationship", from this point it will be so most of the time.