SUNWcsu
mconnect opens a connection to the mail server on a given host, so that it can be tested independently of all other mail software. If no host is given, the connection is made to the local host. Servers expect to speak the Simple Mail Transfer Protocol (SMTP ) on this connection. Exit by typing the quit command. Typing EOF sends an end of file to the server. An interrupt closes the connection immediately and exits.
Postel, Jonathan B Simple Mail Transfer Protocol, RFC 821 August 1982, SRI Network Information Center