Did you remember about the great and free services by Google Apps which offer you a free 50 e-mail accounts with your domain name behind it (firstname.lastname@example.org)?
Nowadays, that service is no longer free, but for you who already registered there still can use their service for unlimited time. And, how about the others who want to have this free service?
Please don’t be panic after seeing this pricing table. For my self, an e-mail with my own domain name is very important and after search for several hours and days, finally i found another great and free service which can be used for unlimited email accounts.
This service is provided by Microsoft Live (which already updated into Outlook mail), what you have to do is create an administrator e-mail address on Outlook.com (its free), then go to this page, sign in then follow the instructions and done!
But, in my opinion this Microsoft Live domain email is more difficult to configure than the Google Apps. You have to at least understand every inch of options available on your CPanel since this service need to integrate with several functions on your CPanel like MX Entry, etc.