An email passes through multiple servers that help ensure it arrives en el right place. That email message flow uses a systematic process based on a number of long-established technical standards.
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Comprender el flujo de mensajes de correo electrónico, desde el envío hasta la entrega
For most users, how an email message flows from the sender to a recipient’s inbox is something that happens behind the scenes. When an individual or an organization sends an email, the message travels from its point of origination, such as an email client where it was composed, across the Internet to its destination. Along the way, it passes through multiple servers that help ensure it arrives at the right place. That email message flow uses a systematic process based on a number of long-established technical standards.
¿Cómo fluye un mensaje de correo electrónico?
Email has been around since the 1960s, when the creators of nascent computer networks began devising ways to send messages to each other. In those early days, users were limited to communicating only with others on the same shared mainframe system. However, the adoption of standard protocols and the interconnection of systems into the shared network we now know as the Internet allowed different mail systems to “talk” to each other.
It’s these standards that allow us to send email messages to virtually anyone. When someone sends an email message, it flows through a series of steps to reach its destination.
Cuando una persona escribe un mensaje, suele hacerlo en un cliente de correo electrónico como Outlook o Apple Mail, o en un servicio web como Gmail.
However, when the message is a correo electrónico transaccional like a shipping notice or a password reset, the message is created automatically by those systems, usually using an email API. (Marketing messages are generated by automated systems as well, although usually in large batches, rather than one at a time like transactional messages.)
In both cases, whether the message is created by an email client or by an automated system, it is specially formatted to be transmitted over the Internet using a standard called “Simple Mail Transfer Protocol” (SMTP).
En sender’s mail server (technically called a “Mail Transfer Agent,” or MTA) looks up the “@domain.com” portion of the recipient’s email address in a Domain Name System (DNS) server to determine which destination mail server (referred to as a “Mail Exchanger,” or MX) it should contact to deliver the message.
En sending and receiving servers communicate using the SMTP protocol. The receiving server accepts the message so that it can be delivered to the recipient.
The recipient’s email client retrieves the message using standards like the Post Office Protocol (POP) or Internet Message Access Protocol (IMAP) to download the message so it can be read.
¿Cómo descargan un mensaje los clientes de correo electrónico?
Web-based email services like Gmail or Hotmail/Outlook.com use their own internal protocols to manage email. But when recipients use a stand-alone email client on a phone or desktop computer, that software uses standard protocols to download messages from mail servers.
Cuando el destinatario utiliza POP, el servidor le entrega todos los correos nuevos y sólo conserva copias de ellos si se marca una opción en el cliente de correo electrónico, si procede. Si el servidor no tiene copias de los correos y el destinatario sufre una pérdida o fallo de hardware, esos mensajes desaparecen para siempre, a menos que los remitentes tengan copias de ellos.
Cuando el destinatario utiliza IMAP, el servidor sincroniza el contenido del buzón, incluidos los elementos enviados y otras carpetas, con cada dispositivo que se conecta a él. Los mensajes permanecen en el servidor, y cuando el estado de uno cambia (por ejemplo, se lee o se borra), ese cambio se propaga por todos los dispositivos cuando vuelven a conectarse.
La posibilidad de conservar y sincronizar mensajes en varios dispositivos es la razón por la que la mayoría de los servicios de correo electrónico actuales utilizan IMAP en lugar de POP.
Más información sobre el flujo de mensajes de correo electrónico
Email involves many different steps and systems. You can learn more about the inner workings of email delivery with these resources:
Email: This Wikipedia article delves into the history of email as well as its many technical details. It links out to several supporting articles that flesh out the main subject.
Email API: Learn more about how e-commerce and other systems can generate transactional email very efficiently.
Entrega de correo electrónico en la nube: Learn more about how systems the SparkPost email delivery service work to make large-scale email transmission and delivery practical.