Was curious if anyone had some thoughts if this is possible (I think it should be, but not sure where to start or how to go about it.)

I would like to create a site that allows people to create an email address, but give them the option to select from several different domains. Any thoughts on how this could be done?

Example:
They would go to www.home.com
And then create an email as;
JohnDoe@example1.com or JohnDoe@example2.com, etc.

Any thoughts on how to go about this.
Tim