SMTP

Simple Mail Transfer Protocol. Standard protocol for e-mail transmission between client and mail server as well as between mail servers. The protocol has undergone many enhancements since the first version in 1982, e.g.:

• RFC 821 in August 1982: Definition of SMTP
• RFC 2487 in January 1999: Encrypted transmission via TLS
• RFC 2821 in April 2001: Revision of SMTP and integration into the DNS