<P> SMTP can trace its roots to two implementations described in 1971: the Mail Box Protocol, whose implementation has been disputed, but is discussed in RFC 196 and other RFCs, and the SNDMSG program, which, according to RFC 2235, Ray Tomlinson of BBN invented for TENEX computers to send mail messages across the ARPANET . Fewer than 50 hosts were connected to the ARPANET at this time . </P> <P> Further implementations include FTP Mail and Mail Protocol, both from 1973 . Development work continued throughout the 1970s, until the ARPANET transitioned into the modern Internet around 1980 . Jon Postel then proposed a Mail Transfer Protocol in 1980 that began to remove the mail's reliance on FTP . SMTP was published as RFC 788 in November 1981, also by Postel . </P> <P> The SMTP standard was developed around the same time as Usenet, a one - to - many communication network with some similarities . </P> <P> SMTP became widely used in the early 1980s . At the time, it was a complement to Unix to Unix Copy Program (UUCP) mail, which was better suited for handling email transfers between machines that were intermittently connected . SMTP, on the other hand, works best when both the sending and receiving machines are connected to the network all the time . Both use a store and forward mechanism and are examples of push technology . Though Usenet's newsgroups are still propagated with UUCP between servers, UUCP as a mail transport has virtually disappeared along with the "bang paths" it used as message routing headers . </P>

Smtp is a protocol used for which of the following functions