Difference Between SMTP and IMAP

Edited by Diffzy | Updated on: March 04, 2023


Difference Between SMTP and IMAP Difference Between SMTP and IMAP

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Since emails are the lifeblood of sales, you would be most surprised if you had read enough about how to make good use of emails as a channel of outreach. This would be the most acceptable way for you to be amazed by this. Email marketing has a return on investment (ROI) that is an incredible 4,200%, which means that you earn $42 for every $1 spent on it. This is referred to as a return on investment multiplier. The study's findings provide evidence of how effective outreach through email can be.

The Simple Mail Transfer Protocol (SMTP) and the Internet Message Access Protocol (IMAP) are examples of email protocols. SMTP and IMAP are acronyms for "Simple Mail Transfer Protocol" and "Internet Message Access Protocol," respectively. Email protocols, in their most basic form, function to create a link between the sender, the email server, and the recipient.


The primary distinction between SMTP and IMAP is that each protocol is designed to perform a unique set of tasks. The purpose of SMTP is limited to the transmission of messages, but IMAP may also be used to manage and retrieve email messages. SMTP is required for an electronic message to be sent from a sender to an email server and carried between two email servers once it has been transferred. On the other hand, you will need to use IMAP to retrieve an electronic message that has been saved on an email server.

IMAP (Internet Access Message Protocol) and SMTP (Simple Mail Transfer Protocol) are the two technologies used in sending and receiving email messages. SMTP is an acronym that stands for "Simple Mail Transfer Protocol." The primary distinction between the two is the role that each of them plays in the system. SMTP is the protocol for delivering email, whether the email is coming from the client or from one server to another. This protocol ensures that the email is sent to the correct location. IMAP, on the other hand, is a protocol that focuses on managing email messages and their retrieval from the server. If you use email, you are most likely already familiar with both protocols, even if you aren't aware of them.

Another significant distinction between SMTP and IMAP is the context in which each protocol is used. IMAP is only utilized in the connection that exists between the client that is obtaining the email and the server that is storing the email. On the other hand, SMTP is used by clients to send emails to a server, but servers also use it to push the email to another server. This is particularly true when the sender and the receiver do not belong to the same service provider.

POP3 is just one of the various protocols used to retrieve email; IMAP is only one of them. IMAP is the more capable of the two protocols often used to retrieve email, although POP is the more common of the two. POP3, on the other hand, is still widely used even though older devices do not natively support it. When sending emails, SMTP is, without a doubt, the protocol that is used most often. Although several protocols are available, SMTP is the most used and widespread outgoing email protocol.

There is no need to deal with or even know the protocol used for browser-based email services, and there is also no need to know the exact addresses utilized for these protocols. When you send and receive emails with a different client, such as Microsoft Outlook or Mozilla Thunderbird, it is only essential for you to be aware of these data. You may be able to acquire two relevant addresses, one for SMTP and another for either IMAP or POP3, depending on which service providers you use. If you do not have these addresses set correctly in your client, you will not be able to send emails, receive emails, or do either.

Difference Between SMTP and IMAP in Tabular Form

Table: SMTP vs. IMAP
Parameters of Comparison
Full form
SMTP full form is Simple Mail Transfer Protocol.
IMAP's full form is the Internet Message Access Protocol.
This Means
The Simple Mail Transfer Protocol (SMTP) is an email protocol that creates a mechanism for electronic communications to be moved from a sender to an email server and between two email servers. It does this by establishing a way for email servers to communicate.
IMAP is an email protocol that organizes electronic messages and retrieves them from an email server. It does this by using a directory structure.
The only purpose of the Simple Mail Transfer Protocol (SMTP) is to transmit electronic messages to a server or between servers.
IMAP is an acronym that stands for Internet Message Access Protocol. Its purpose is to control and retrieve electronic communications from a server.
The Simple Mail Transport Protocol (SMTP) transfers electronic communications between servers and clients.
The only direction in which IMAP may send electronic communications is from a client to an email server.
SMTP may operate on port 25, the industry standard for email transmission; port 465, which is not RFC compliant; port 587, which is TLS encrypted; and port 2525. (not an official port, but it supports almost every email service).
Both port 143 (the default port without encryption) and port 993 (the secure SSL/TLS port sometimes referred to as IMAPS) may be used for IMAP.

What is SMTP?

The standard protocol used by the email service industry, SMTP, is text-based communication. It does this by putting in place a system that allows electronic communications to be sent from a sender to an email server and between two email servers. The abbreviation for "Simple Mail Transfer Protocol" is SMTP. The sole purpose it serves is to "send" messages.

An SMTP client delivers instructions to an SMTP server in the form of messages such as "HELLO," "MAIL," "RCPT," and so on. SMTP servers will respond to these messages with numeric completion codes such as 220, 250, 354, etc. The transmission of electronic communications from one party to another with the help of this workflow.

In the 1970s, the mechanisms that underpin SMTP were created. Usenet was a communication network that emerged at about the same time as SMTP servers and had many characteristics. After that, throughout the 1980s, SMTP gained popularity as an alternative to UUCP mail because it was complementary to UUCP mail (Unix to Unix Copy Program).

At the moment, IceWarp, Sendmail, Exim, Postfix, MagicMail, MailEnable, and HMailServer are all examples of servers SMTP is compatible with and supports. Mozilla Thunderbird (after version 82.0) and NMH are examples of clients it is compatible with (after version 1.7).

The email client (such as Gmail, Thunderbird, Outlook, and so on) will use a protocol known as Simple Message Transfer Protocol (SMTP) to transmit your email messages to your email server. It is common for the email server to be hosted by the company that provides you with email services, such as Google; however, your Internet service provider (ISP) may also host the server (most often by the same one that hosts your domain). Next, the email server will use SMTP to deliver your message to the inbox located on the email server that belongs to the receiver.

It is a protocol that allows information to be sent from one computer to another using email addresses as the link in the chain of communication. SMTP is the protocol that is used while establishing communication guidelines between servers. It provides a variety of channels of communication, such as broadcasting a single message to a large number of users, transferring audio and video files, and so on. It can handle errors and will respond to messages indicating that there was an issue.

What is IMAP?

IMAP stands for Internet Message Access Protocol. It is a communication standard protocol for email services. It creates a system that allows for the retrieval of electronic communications from a server that stores email. The server will never delete these communications from its database. The protocol automatically downloads the file whenever the recipient launches the program and selects a message to read.

IMAP is designed only to handle and receive messages when they are requested. In contrast to SMTP, the transmission will only occur between a server and a client. Three different types of answers may be received from an IMAP server: a Status Response (OK, BYE, BAD, or NO), Server Data (CAPABILITY, EXIST, or FETCH), or a Command Continuation Request.

Nearly all implementations of IMAP allow many devices to connect with the server at the same time. On the other hand, the communication service provided by IMAP is comparable to that offered by POP3. POP3 compiles all electronic correspondence into a single virtual "mailbox." When the recipient launches the application, the download is completed in its entirety.

Mark Crispin first conceived of IMAP as a remote access mailbox protocol, and he was the one who built it. The most recent version of IMAP2bis was just made available after undergoing various updates and revisions. After some time, it was renamed IMAP4 so that nobody would be confused.

It is a protocol that runs at the application layer and functions as a contract for receiving emails from the mail server. It was intended to be used as a protocol for remote access to mailboxes, and the most recent version of IMAP is IMAP4. It is the protocol that is used the most often for obtaining emails from servers. There are a few other names for this phrase, including Internet mail access protocol, Interactive mail access protocol, and Interim mail access protocol.

Main Differences Between SMTP and IMAP in Points

  • While SMTP uses ports 25, 465, and 587 for secure connections, IMAP uses ports 143 and 993 for secure connections (SSL/TSL connections) (TSL encrypted).
  • SMTP was created by RFC 821 in 1982, whereas Mark Crispin created IMAP in 1986.
  • One of the most used protocols for receiving email is IMAP. IMAP allows message syncing across all devices.
  • Messages may be sent from a client to a server via SMTP, and it can also transport messages between servers. On the other hand, IMAP can only send messages in one direction, from a server to a client.
  • IMAP is just one of two extensively used protocols for retrieving email, but SMTP is the most common standard for sending an email. IMAP was developed in the 1990s and is still frequently used today.
  • IMAP users may arrange their emails on the server, but SMTP users can set them on client storage.
  • SMTP transfers data between servers, whereas IMAP facilitates communication between the server and client.
  • SMTP is used to transfer data, whereas IMAP is used to retrieve messages.


Regarding the protocols for sending and receiving messages, SMTP and IMAP has to be used at all times. These connect the email sender, the email server of the receiver, and the recipient of the email. While SMTP is meant to be used for sending messages, IMAP is designed to be used for retrieving messages that have already been sent. The Simple Mail Transfer Protocol, often known as SMTP, is now one of the most used servers. On the other hand, POP3 is a communication protocol that stores all messages in a mailbox and downloads the messages. POP3 is also known as Post Office Protocol 3. POP3 is now in direct rivalry with IMAP as a result of this. This allows the user to view the notes even when they are not online. IMAP is distinguished from other email protocols by its capacity to support multiple simultaneous logins, a feature not offered by other email protocols. Because of this, IMAP is an excellent option for customers who need to be able to access their email from several different devices. Customers with sluggish or unstable internet connections are ideal candidates for the POP3 email protocol.


  • https://www2.rivier.edu/faculty/vriabov/Information-Security-SMTP_c60_p01-23.pdf
  • http://www.hjp.at/doc/rfc/rfc2595.html

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"Difference Between SMTP and IMAP." Diffzy.com, 2023. Thu. 23 Mar. 2023. <https://www.diffzy.com/article/difference-between-smtp-and-imap-1141>.

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