Simple Mail Transfer Protocol (SMTP)

By Won Lee

What is SMTP?

Stands for Simple Mail Transfer Protocol

Used for sending and receiving electronic mail efficiently and reliably

Daily function of life

Used daily by the billions

History of SMTP

SMTP outgrew others in 1970’s. Jonathan Postel wrote the SMTP

definition in August 1982. Documented under Request for

Comments (RFC) 821 Used by small collection of military,

universities, and corporate research laboratories.

Connections were slow and unreliable but was only used by a handful of people.

Hist of SMTP (cont.)

Number of hosts were recognizable by each other.

Focused on Reliability rather then Security. People helped by configuring system to

“open relay”. Meaning a configured host would accept

any mail meant for other systems and relay it to the mail’s final destination.

First spam in 1978 by Salesman from DEC

SMTP Specifications

SMTP mail transaction is a text-based protocol that is done in three steps.

Firstly, the transaction starts with a MAIL command that gives the sender identification.

Followed by a series of one or more RCPT commands, giving the receiver information.

Finally, a DATA command initiates transfer of the mail data and is terminated by the “end of mail” data indicator, which also confirms the transaction.

SMTP is mainly delivery protocol and uses POP3 or IMAP to receive messages that’s being queued.

Visual Specification

Privacy

Not encrypted

Email passes through intermediate computer

Internet Service Provider (ISP) holds backup copies

Security

Rise of Con artists, hackers, & spammers

Wasn’t based on security to start with

Hard to retrofit a new security mechanism onto something widely used as SMTP.

Pervasiveness

Choice of easy and fast communication throughout the world.

247 billions emails sent daily

90 trillion sent in year 2009

Reliability

Was based on Reliability

Emails do get lost due to crowded and spammed servers

Unpredictable timeliness between sender & receiver

Interoperability

No point of emails if it’s not interoperable

Anywhere around the world

To any connected device (i.e. PC’s to Smart Phones)

Support of the Community Anybody that is a

member of the IETF

Has been updated many times in different RFCs

Shares ideas how to keep unwanted emails out (i.e. spam, hackers)

Ease of Use

So easy a kid can do it

User friendly software/interface

No coding necessary, unlike old times.

Application of SMTP

Almost any device with internet connectivity.

Web based mail: yahoomail, gmail, hotmail, and many more that nobody even heard of.

Software such as; Outlook Express, Mozilla Thunderbird, Iphone, Blackberry.

Can be used for personal or business use.

Conclusion

It’s makes life very easy to communicate with people around the world.

Fast, cheap, and easy to use.

Definitely be around in the future because of its convenience.