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What is Simple Mail Transfer Protocol (SMTP)?

by Iwan Price-Evans on Web technology • June 16, 2022

The Simple Mail Transfer Protocol (or SMTP) is a standard for sending electronic mail across networks. It was developed in 1982 by Ray Tomlinson at BBN Technologies.

What Does SMTP Do?

SMTP is the protocol that allows users to send e-mail through a network. This includes the internet, intranets, local area networks, and other private networks.

SMTP is used by email servers to send messages from one server to another. It is also known as the mail transfer agent or MTA.

Why Should I Care About SMTP?

If you use Gmail, Yahoo! Mail, Hotmail, AOL, or any other web based email service, then you should care about SMTP because it is how these services communicate with each other.

How Can I Configure My Server To Send Email Using SMTP?

You can configure your own server to send emails using SMTP. This is done through the configuration files located at /etc/postfix/main.cf and /etc/postfix/*.cf. These files contain the settings needed to make your server work properly.

How Can I Test Whether My SMTP Server Works Correctly?

To test whether your server works correctly, use telnet to connect to port 25 of your server. If you receive a connection refused error message, then your server does not accept connections on port 25.