Delivermail

The ancestor of sendmail, delivermail used the FTP protocol on the early ARPANET to transmit e-mail to the recipient.

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 in 1982, the road was paved for MTAs that no longer relied on FTP for delivery. The new protocol for sending mail was SMTP, and after DNS replaced hosts files[?], delivermail evolved into sendmail, which is still the most widely used MTA on UNIX systems today.