Found this on a marketing blog:
Your email address can brand you as a sports fan, a car buff, an athlete, an alcoholic or someone who’s, let’s say, sexually adventurous. It can brand you by profession, by school, by hobby, or it can brand you as old and inflexible
via AOL Email Address Brands You As Technologically Obsolete | Personal Branding Blog – Dan Schawbel.
This is absolutely true of dentistry. If you send your patients an e-mail with the return address of DrJimbo@aol.com you can rest assured half your patients will think you are hopelessly techno feeble and the other half will think you are a fool.
This is one of the best reasons to get your own domain name. And get it immediately even if you do not have an active web site. Then you can use your domain for your e-mail.
Feeble = DrJimbo@aol.com
Professional = jsmithdds@smithdentistry.com
If you are interested in buyings your domain name one of my favorite domain registrars is Go Daddy. By the way there is no reason to have just one domain, get as many as you want using all sorts of variations on your name and practice name.