The Simple Mail Transfer Protocol, or SMTP, is the standard protocol used to send electronic mail from one server to another across a computer network. American computer scientist Jon Postel published the first SMTP specification in 1982, building on earlier ARPANET mail-transfer experiments carried out during the 1970s. SMTP still handles the sending side of nearly all email delivered across the internet today, typically paired with separate protocols such as IMAP or POP3 that let a recipient retrieve mail waiting for them on a server.
Facts
Partially Attested
YearThis source dates SMTP's origins to 1980. Jon Postel published the first document titled Simple Mail Transfer Protocol (RFC 788) in November 1981, and the definitive specification RFC 821 is dated August 1982. SignificanceDefined to transfer electronic mail reliably and efficiently between hosts. 1 FAQs
How does a message actually get passed along when it is sent over SMTP?
It is a lock-step dialog of MAIL and RCPT commands followed by the message data.
A sending server opens a two-way channel to a receiving server. The sender issues a MAIL command naming the sender of the message, then a RCPT command for each recipient. The receiver answers each step with an OK reply, or it can reject a single recipient without rejecting the whole transaction. Once the recipients are settled, the sender transmits the message data, ending with a special sequence, and the receiver confirms with a final OK reply. The dialog is deliberately lock-step, one command at a time.
Connections
In Field
Source Wikipedia: Simple Mail Transfer Protocol
Sources
1. RFC 821: Simple Mail Transfer Protocol
Section 1, IntroductionQuote, Section 1, Introduction
The objective of Simple Mail Transfer Protocol (SMTP) is to transfer mail reliably and efficiently.
2. Wikipedia: Simple Mail Transfer Protocol
Lead section, fifth sentence
SMTP's origins began in 1980, building on concepts implemented on the ARPANET since 1971.
- In Group: Internet Communication Protocols, lead sentence: an Internet standard communication protocol for electronic mail transmission
In Field: Software Engineering, Categories
Internet mail protocols
View the SourceReader Challenges (0)
No disputes yet. Spotted an error or a better source? Open the first one.
Sign in to dispute this or suggest a correction.