In this day and age email is getting more popular as a way of communicating. I have my email on my business cards and every so often a customer will email me instead of picking up the phone. It can be a quick and easy way for a busy customer to talk to you. Respect their way of communication and it will go a long  ways. Some of my best customers use email and I get a lot os repeat business this way too. This is part of putting the customer first.