What is SMTP

SMTP stands for Simple Mail Transfer Protocol, a TCP/IP standard protocol used to send and receive email between servers. SMTP is an application layer protocol and one of the most common and commonly used protocols for email communication over the Internet; if the client wants to send mail, it needs to open a TCP connection with the SMTP server and then send the mail through the connection.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

SMTP, or Simple Mail Transfer Protocol, is a TCP/IP standard protocol for sending and receiving email between servers; it is also known as RFC 821 and RFC 2821.

Basics of SMTP

SMTP is an application layer protocol for email communication (transmitting and delivering emails) over the Internet ) is one of the most common and commonly used protocols; is created and maintained by the Internet Engineering Task Force (IETF).

If the client wants to send emails, it needs to open a TCP connection with the SMTP server, and then send emails through the connection. The SMTP server is always in listening mode, and as soon as it listens for a TCP connection from any client, the SMTP process initiates a connection on that port (25); the client process sends the mail as soon as the TCP connection is successfully established.

Key Components of SMTP

SMTP is often integrated into email client applications It consists of four key components:

1. A local user or client utility called the Mail User Agent (MUA)

2. A server called the Mail Submission Agent (MSA)

3. Mail Delivery Agent (MDA)

4. Mail Transfer Agent (MTA)

SMTP passes between the user and the server It works by initiating sessions between networks, and it moves emails on and between networks, sending emails from one server to another; while MTA and MDA provide domain search and local delivery services, SMTP interacts with emails Transport agents (MTAs) work closely to deliver messages to the correct computers and email inboxes.

Advantages of SMTP

1. SMTP is an open standard, so any application can use this protocol to send emails from clients to transmitted to the server.

2. The rules governing this protocol are simple and comprehensively defined, making it very reliable and predictable.

3. Because this protocol has been widely adopted, there is no compatibility problem when sending messages between SMTP servers.

4. High flexibility

SMTP working principle:

1. Send emails using SMTP

When you click the send button when you choose to send bulk emails in Office 365, Zimbra, G-suit or on other platforms, it will automatically connect to SMTP server and provide it with your email details. The server will carry the email, identifying the receiver and the receiver's domain. If the receiver uses the same domain as yours, the message is sent immediately.

If the receiver is using a different domain, hand over the email to IMAP or POP to sort the server for mail delivery. While SMTP is the postman for your email, when the recipient is not using the same domain as the sender, mail delivery is left to IMAP and POP.

All of this happens quickly in a short period of time, so you cannot observe the complexity and have no idea what will happen when you hit the send button on your computer. Just like searching for a topic on Google, it happens so quickly that you don't need to worry about how it works.

2. Send email using IMAP or POP

We have discussed the virtual postman and how it distributes work to IMAP and POP, let’s take a closer look at them. How email works and provide yourself with a mechanism for running email.

To find your email receiving server, SMTP connects to the Domain Name System (DNS) and uses the IP address to identify the receiving server. Once the process is authenticated, your email is delivered to the delivery boys: IMAP and POP, whose responsibility it is to deliver your email, and they will do so all the time.

Additionally, while the job of sorting out email lies with your SMTP server, the more complex task of delivering email may be left to IMAP or POP. Because these systems work together, your emails are sent very quickly, unless the email address is fake or spam.

Fraud emails and spam lead us to the topic below that you should know about, how SMTP works:

For more related knowledge, please visit the FAQ column!

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