What is SMTP protocol and how does it work?

Hello Friends, In this blog post(What is SMTP protocol and how does it work) I am going to let you know about the SMTP server, What is the SMTP server and how do they work in the network with email?

What is the SMTP protocol and how does it work?

SMTP stands for the simple mail transfer protocol. SMTP is one of the most common uses of networks is electronic mail, the ability to send a message or file to a specific user at a local or remote site.|What is SMTP protocol and how does it work|

Typically, you send a message by specifying the email address of the recipient.

The usual address format is name@host-text-address.

The message is buffered at the destination site and is accessible only by the intended user.

In addition to the message formats, the TCP/IP protocol suite specifies a standard for the exchange of mail between machines.

That is, the standard specifies the exact format of messages a client on the machine uses to transfer mail to a server on another.

The standard transfer protocol is known as a simple mail transfer protocol.

The SMTP protocol focuses specifically on how the underlying mail delivery system passes messages across the internet from one machine to another.

It does not specify how the mail system accepts mail from a user interface that presents the user with incoming mail.

SMTP does not specify how mail is stored or how frequently the mail system attempts to send a message.

SMTP interacting with local mail and TCP
Fig1 SMTP interacting with local mail and TCP

Fig 1 shows the interaction between local mail SMTP, and TCP, when a user sends mail, the local mail facility determines whether the address is local or requires a connection to a remote site.

In the latter case, the local mail facility stores the mail, where it waits for the client’s SMTP.

When the client SMTP delivers the mail, it first calls TCP to establish a connection with the remote site.

When the connection is made, the client and server SMTPs exchange packets and eventually deliver the mail.

At the remote end, the local mail facility gets the mail and delivers it to the intended recipient.

There are four parameters in the SMTP protocol.

Sending Mail:

To send mail the user through the US(user agent) creates mail that looks very similar to postal mail.

It has an envelope and a message.


The envelope generally contains the sender’s address, the receiver’s address, and other information.


The message contains the headers and the body. The headers define the sender, the receiver, the subject of the message, and some other information.

The body contains the actual information to be read by the recipient.

Receiving Mail:

The user agent periodically checks the mailboxes. If a user has mail, the UA informs the user first by giving notice.

If the user is ready to read the mail, a list is displayed in which each line contains a summary of information about a particular message in the mailbox.

आप नीचे दिए हुए कुछ इम्पोर्टेन्ट ब्लॉग लिंक्स को भी पढ़ सकते है |

What is Ethernet….?
Difference between token ring, Ethernet, and token bus networks….?
What is a token ring….?
OSI Model In Hindi…
Classless Addressing vs Classful Addressing In Hindi…
Internet Security Threats…
Dijkstra’s Algorithm: Shortest Path Routing Algorithm…
Caesar Cipher & Mono Alphabetic Cipher…
What are the types of network security…
SMTP: Simple Mail Transfer Protocol…
What Is VPN: Virtual Private Network…
HTTP: HyperText Transfer Protocol…
Token Bus In Hindi…

In the case of any queries, you can write to us at a5theorys@gmail.com we will get back to you ASAP.

Hope! you would have enjoyed this post What is SMTP protocol and how does it work?

Please feel free to give your important feedback in the comment section below.

Have a great time!


I am a blogger by passion, a software engineer by profession, a singer by consideration and rest of things that I do is for my destination.