Everywhere I look, I see people who have their email address on their business card, and it's the email address given to them by their ISP (eg; spottedpaints@my_dialup.com). Very often these people will already have their own domain for their web site, but do not use this domain for their emails.

Every time you tell someone your email address, hand out a business card, or send someone an email, this is an opportunity to increase your brand awareness. People are more likely to remember your business and/or web site if your email is using your domain (eg; sales@spottedpaints.com). Not only does it look more professional and show that you're serious about your business, it also has another very important advantage.

Imagine you've given out your email address spottedpaints@my_dialup.com to thousands of your contacts. One day you decide to change your ISP (perhaps you've found a better deal). Your old email address is now invalid, and you have to contact those thousands of people again to give them your new email address. As well as being inconvenient, it's very unprofessional. By having your own domain, you never need to change email addresses again !

These days, domains are so affordable, there's really no excuse for not having one, and if you do already have one, you should be using it for your emails as well. Why advertise you ISP ? They already have a large advertising budget and don't need your help.