 By far the most commonly used of these piggyback protocols was "Echomail", public discussions similar to Usenet newsgroups in nature.Echomail was supported by a variety of software that collected up new messages from the local BBSes' public forums (the "scanner"), compressed it using ARC or ZIP, attached the resulting archive to a Netmail message, and sent that message to a selected system.On receiving such a message, identified because it was addressed to a particular "user", the reverse process was used to extract the messages, and a "tosser" put them back into the new system's forums.