Computers use the TCP/IP protocol suite to send email messages in the form of packets. The internet Mail applications Consortium maintains a comprehensive list of email RFCs. Some of the key RFCs are listed below:

• RFC 1939; Post Office Protocol
• RFC 2060; IMAP
• RFC 2076; Common Internet Message Headers
• RFC 2821; Simple Mail Transfer Protocol
• RFC 2822; Internet Message Format

Instant Messaging allows real-time communication between two or more users. It also allows users to determine who is immediately available for communication at any given time.

While it is primarily known as a way for people to chat with friends over the internet, instant messaging has many other uses and is becoming increasingly important:

• Voice Chat
• Video Conferencing
• File Sharing
• Customer service

Email and Instant Messaging over Satellite uses a star network where each user terminal inter-connects via satellite with a hub to gain access to a wide variety of multimedia services. The communication between the hub and the user terminal is done solely through satellite links, a Return Link (from the user terminal to the hub) and a Forward Link (from the hub to the user terminal).