Sendmail was one of the first programs to route messages between networks and today is still the dominant e-mail transfer software. It thrived despite the awkward ARPAnet transition between NCP to TCP protocols in the early 1980s and the adoption of the new SMTP Simple Mail Transport Protocol, all of which made the business of mail routing a complex challenge of backward and forward compatibility for several years. There are now over one million copies of Sendmail installed, representing over 75% of all Internet mail servers.
Simultaneously with the announcement of the company in November 1997, Sendmail 8.9 was launched, featuring new tools designed to limit junk e-mail. SendMail 8.9 is still distributed as source code with the rights to modify and distribute.
sendmail -bv ADDRESScan be used to learn what the local mail system thinks of ADDRESS. You can also talk to the Sendmail daemon on a remote host FOO with the command
telnet FOO 25(1998-08-25)