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RFC 821

A cornerstone of email history

RFC 821, or “Request for Comments 821”, is a technical document published in August 1982 that defines the SMTP protocol (Simple Mail Transfer Protocol).

SMTP is the standard for email transfer over computer networks.

This technical specification describes how email servers should send, receive and relay email messages.

It establishes the rules and procedures that ensure effective communication between mail servers around the world.

Relevant historical data

The origin of RFC 821 goes back to the early days of the Internet, when it was still known as ARPANET.

At that time, the need for standardized communication between different systems became apparent.

This was caused by the growing network of computers that needed to exchange information efficiently.

Jon Postel, a prominent figure in the development of the Internet, was the author of RFC 821, marking an important point in the history of email.

Before the introduction of SMTP and the publication of RFC 821, email sending methods were rudimentary and non-standardized.

This resulted in a lack of interoperability between different systems.

Key considerations

One of the main considerations of RFC 821 is its focus on simplicity and efficiency

The protocol was designed to be flexible enough to work on different systems and networks.

But also robust enough to handle message transmission reliably.

SMTP, as defined in RFC 821, uses simple textual commands and responses that facilitate communication between servers, even under variable network conditions.

In the context of email marketing, the standardization offered by RFC 821 and SMTP is fundamental.

It allows marketers to send large quantities of emails, such as newsletters and promotional emails.

The ability to reach customers directly in their inboxes, regardless of the email service provider they use, is a direct benefit of the standards defined in RFC 821.

Why it is important, advantages

The importance of RFC 821 lies in its fundamental role in standardizing email communication on the Internet.

Before its implementation, there was no universal method for exchanging emails, which limited the effectiveness and scope of this communication channel.

By establishing a standard protocol, RFC 821 not only facilitated interoperability between different systems and networks, but also laid the foundations for the exponential growth in the use of email in personal and professional environments.

The advantages of RFC 821 are wide and varied.

From a technical perspective, it provides a framework that guarantees the reliable delivery of email messages, regardless of the complexity of the underlying network.

For companies and marketers, this means that they can rely on email as an effective tool for reaching their audiences.

To communicate important messages and foster relationships with customers and potential customers.

In the area of email marketing, the standardization of SMTP has made it possible to develop sophisticated and personalized marketing strategies, maximizing return on investment and strengthening brand loyalty.


In short, RFC 821 is not just a technical document that defines a communication protocol.

It is a pillar that has enabled the development and expansion of email as an indispensable tool in the modern world.

Since its publication in 1982, it has been instrumental in ensuring that email messages are transmitted efficiently and reliably across the countless networks and systems that make up the Internet.

For marketers, the legacy of RFC 821 is the ability to use email marketing as a powerful form of direct, personalized and effective communication, capable of reaching global audiences with ease.