A No Soliciting Simple Mail Transfer Protocol (SMTP) Service Extension
SMTP
Simple Mail Transfer Protocol
unsolicited bulk email
ube
no soliciting
solicitation class keywords
solicitation mail header
trace fields
This document proposes an extension to Soliciting Simple Mail Transfer Protocol (SMTP) for an electronic mail equivalent to the real-world "No Soliciting" sign. In addition to the service extension, a new message header and extensions to the existing "received" message header are described. [STANDARDS-TRACK]