What Are All Applications Of SMTP Transmission Protocol?

Marketing   |   12 March, 2021   |   450   |   3980

SMTP is a widely used communication protocol for the transmission of electronic mails. This particular protocol has the widespread usage today. A lot of message transfer agents and mail servers are using this simple mail transfer protocol in order to send and receive the mail messages. When it comes to SMTP servers, they are commonly using the TCP (Transmission Control Protocol) on the port number 25.

Mail processing model with SMTP:

In the process of sending or receiving the emails, the email is submitted by the mail user agent or mail client to the mail server or mail submission agent with the help of SMTP protocol on the TCP port number 587. Most of the mail box providers allow this email submission typically on the port 25. The mail submission agent (MSA) delivers the email message to its mail transfer agent (MTA). These two agents are frequently instances of the similar software launched with the various options but on the same system. The local mail processing can be done either in the way of splitting among the several machines or entirely on the single machine.

The email agent processes on a single machine can share files but they transfer the mail messages between each other with the use of SMTP when you are doing this process on the multiple machines. Every email process is an SMTP server in its own. The set of communication guidelines mentioned in the SMTP protocol used by the different numbers of email servers in order to deliver the mail messages to the client systems. All your emails are just the series of text when it comes to the communication language. But this simple mail transfer protocol helps the email clients and servers in order to categorize and also organize the details you send. While sending any mail message, the receiver, sender, title heading, and also email body are separated into the different sections. This simple mail transfer protocol (SMTP) separates such sections using some secrete code words.

Usage of SMTP:

• SMTP or Simple Mail Transfer Protocol is generally used to send the mail messages so it is only to send the outgoing messages not for receiving the mails in the receiver end.


• The correct SMTP server can only have an ability of sending the emails when you set up your own email client system.


• Unlike IMAP and POP3 protocols, this SMTP can’t be used to store and retrieve the mail messages. This is because it is always responsible to setup the communication between the servers.


• The first server finds itself and transmits the particular kind of operation it performs.


• The mail message is sent only after another server gives an authorization to that process.


• SMTP is highly reliable and also simple process to send the emails but not highly secure since it is text based. This is why this specific protocol for email sending process is somewhat vulnerable to spoofing.

SMTP is actually considered as the text based and connection oriented protocol in which the sender of the emails communicates with the email receiver by just issuing the series of commands and supplying the needed data over the trusted ordered data stream channel. This kind of activity has been done through a particular connection which is known as TCP (Transmission Control Protocol) connection. This SMTP session has the commands which are originated by the SMTP client system and also the related responses given by the SMTP server system. So, this specific session is opened and the related important parameters are exchanged. This session of simple mail transfer protocol includes 0 or more SMTP transactions which consist of 3 replay or command sequences including,

• MAIL command – This command is mainly to set up the return address which is also known as reverse path, return path, mfrom, bounce address, or cover sender.


• RCPT command –This particular command is very helpful to establish the receiver of the email and it can be given several times for the different recipients.


• DATA command – It is mainly to indication the starting of the message writing or the matter of the email as oppose to its envelope.

The reply from each server can be either positive or negative. The drop is the positive response given when the message discard instead of delivery. The reject is the negative response which implies the permanent failure.