At my urging, friends just bought a Mac after 10 years on a PC and while they are thoroughly enjoying it, they've come to me now and them for orientation help. A problem I can't solve is how to delete an eMail address. They had my old eMail address at bellsouth.net and have added my new one at comcast.net. When they start an eMail to me, the system defaults to my old address and they have to make the substitution. I can't figure out how to delete the bellsouth.net address from their address book and the Help component doesn't show me. They're using the Mail program that came bundled with the computer.

Thanks.