Many small business owners do this same thing, instead of promoting their own business they promote a huge corporation. They do this with out even realizing it. You market yourself through the email you use. How many of you right now are using .aol, .hotmail, .gmail or any other free email service? Yeah it's great that you get a free email address, but think about the real cost of that email address. You are NOT promoting your own business, and that is costly.
Very often people will see your email address and nothing else about your business, now if they just see "email@example.com" what do they know about your business? Nothing. There is no way to research your business any further, take it a step further and now they know you are an AOL user, Yuck, but that's a story for another blog post :).
Now look at this email "RKaplan@ProntoPlumbing.com", First of it's much more professional, second you are promoting your website domain. Now if a potential customer comes across your email address, they at least have a path to your website where they can learn more about your services and pick up the telephone and call you.
This is the simplest and least expensive form of advertising you can do for your plumbing business. It adds a new level of professionalism and an easy way for potential customers to find you.
Make today they day you cut the cord on your free email service and start promoting your own company.