With my current workload I am spread very thin.   Email, while being extremely convenient in a lot of cases, has also created some problems.

If you have a number of questions regarding an order that you may be about to place it is much quicker to take care of these with a quick phone call.   If you have 1 or 2 short questions that are not urgent and require brief answers, then by all means use email.

Another consideration is time in returning email.   I generally sit and answer emails one or twice a week.   When I am vacationing with my family or away on a hunting trip, I don't answer them until I return.   This has created a situation where the customer, or potential customer, thinks that they are being ignored and that's simply not the case.