Communication via e-mail is by far the most common Internet activity. You can(71 )with anyone in the world who has an Internet address or e-mail(72)with a system connection to the Internet. All you need is(73)the Internet and an e-mail program. Two of the most widely used e-mail programs are Microsoft's(74)and Netscape's Navigator. A typical e-mall message has three basic(75): header, message, and signature.