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What is SMTP-AUTH? Introducing the mechanism and security measures for SMTP communication
2020-03-26(Updated: 2024-12-28 )


This time, we will introduce "SMTP-AUTH".

Table of Contents [Hide]

1. The cause of spam? Holes in SMTP
2. What is SMTP-AUTH?
3. Advantages of using SMTP-AUTH
4. Secure email delivery with SMTP-AUTH





The cause of spam? The loophole in SMTP
Before introducing SMTP-AUTH, let's leads for commercial real estate briefly explain how email delivery works.

When an email is created using email software, it is first sent to the sender's email server, then forwarded to the recipient's server, and the email is delivered to the recipient.

When sending email to the recipient's mail server, a protocol (procedure) called " SMTP " is used.






What is a mail server? Learn about the mechanism and role of email delivery!
Learn about the different individual mail servers that play different roles in sending and receiving email, and get a complete picture of email delivery.
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Now, SMTP originally did not require user authentication, so anyone could freely request to send email to an SMTP server.

As a result, spam emails, such as advertising emails and virus-containing emails, could be sent indiscriminately.





To avoid this, measures such as "IP address restrictions" have been implemented, which allow and receive connections only from specific IP addresses.







However, its weakness was that if the permitted "IP address" was shared among multiple organizations or unrelated individuals, it could be misused, making it an incomplete security measure.




What is an IP address?
An IP address is a number that identifies a device on a network. It is used to avoid misidentifying the other party and plays a role similar to an address or phone number on a network.
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What is SMTP-AUTH?
"SMTP-AUTH" is a method of authenticating the client based on authentication information when communicating from the client to the sending mail server.

To put it more simply, it " authenticates and verifies whether the mail server making the sending request is a legitimate client ."