Electronic mail, abreviated e-mail or email, is a method of composing, sending, and receiving messages over electronic communication systems. The term e-mail applies both to the Internet e-mail system based on the Simple Mail Transfer Protocol (SMTP) and to intranet systems allowing users within one company or organization to send messages to each other. Often these workgroup collaboration systems natively use non-standard protocols but have some form of gateway to allow them to send and receive Internet e-mail. Some organizations may use the Internet protocols for internal e-mail service.