Mail-11

Mail-11 was the native email transport protocol used by Digital Equipment Corporation's VMS operating system, and supported by several other DEC operating systems such as Ultrix.

It normally used the DECnet networking system as opposed to TCP/IP.

Similar to Internet SMTP based mail, Mail-11 mail had To: Cc: and Subj: headers and date-stamped each message.

Mail-11 was one of the most widely used email systems of the 1980s, and was still in fairly wide use until as late as the mid-1990s. Messages from Mail-11 systems were frequently gatewayed out to SMTP, Usenet, and Bitnet systems, and thus are sometimes encountered browsing archives of those systems dating from when Mail-11 was in common use.

Several very large DECnet networks with Mail-11 service existed, most notably ENET, which was DEC's worldwide internal network. Another big user was HEPNET, a network for the high energy physics research community that linked many universities and research labs.

Mail-11 used two colons (::) rather than an at sign (@) to separate user and hostname, and hostname came first.