Complete Protocol dictionary, glossary and reference

ESMTP: Extended Simple Mail Transfer Protocol

Extended Simple Mail Transfer Protocol (ESMTP) is the extended version of the original Simple Mail Transfer Protocol (SMTP), which includes additional functionality, such as delivery notification and session delivery. All the features of ESMTP are included in the latest version of SMTP as defined in RFC 2821 and the ESMTP is no longer necessary.

Standard Organization

IETF

Related Document

RFC 2821