The ancestor of sendmail, delivermail, also by Eric Allman, is a mail transport agent that used the FTP protocol on the early ARPANET to transmit e-mail to the recipient.
[1] Due to deficiencies in using FTP to send e-mail, a new protocol was created in 1981 for sending e-mail, SMTP.
[citation needed] In 1979, when delivermail was first shipped with 4.0BSD and 4.1BSD, the ARPANET was still using NCP as its network protocol.
When the ARPANET switched to TCP/IP at the end of 1982, the road was paved for MTAs which used TCP to deliver e-mail; delivermail evolved into sendmail.
[citation needed] This Unix-related article is a stub.