In this tutorial, we will explain the difference between the SMTP, POP3, and IMAP email protocols. Email protocol is a set of commands for sharing mail between two machines such as computers, and servers. This allows clients to send and receive email. There are a few email protocols, but the most common protocols are POP3, IMAP, and SMTP. In the following paragraphs we explain what defines them and their differences.
SMTP Protocol
The SMTP (Simple Mail Transfer Protocol) is an application layer and connection oriented protocol. It is used to send and receive mail messages by mail servers and other transfer agents. SMTP is a mail delivery and not a mail retrieval protocol. Therefore, it delivers an email to an email provider’s mail server. The SMPT protocol defines a process for exchanging data between an email client and a mail server. Email client is a software application that is used to access, manage, and send emails by the client. It provides users with a user interface for better viewing and organization of the emails.
A mail server is a specialized computer for sending, receiving, and forwarding emails. It is not interacted with by the users, unlike the email clients. SMTP uses TCP (Transmission Control Protocol) as its transport protocol. The first step in sending the email is to have a TCP connection between the client and the server. The special command that initiates the sending process is called the Hello command. Afterwards, the email content such as the email header, email body, and additional components is sent by the client and the MTA (Mail Transfer Agent) checks the domains of the recipient email address. Once the data is transferred, the server closes the connection.
POP3 Protocol
POP3 (Post Office Protocol) is an application layer Internet Standard Protocol. It is used by email clients to retrieve emails from a mail server. It retrieves the messages over TCP/IP connection. The POP3 protocol downloads all the emails from the server and stores them locally on the device. The protocol connects the email client to the server, downloads all emails locally, and the mail server deletes the emails. The transmission of the emails ends when the client disconnects from the server.
There are many advantages of using POP3. It is straightforward to use and, reduces server load because the mails are deleted immediately after they are downloaded. Additionally, it is supported by many clients such as Gmail, Thunderbird, and Microsoft Outlook. Finally, the mails can be managed without Internet Connection since are stored locally.
There are disadvantages as well. The biggest being that there is no backup solution for the mail to be deleted accidentally locally. There is no synchronization, the operations for searching, and folder management are missing and there are data loss risks.
IMAP Protocol
IMAP (Internet Message Access Protocol) is an application layer Internet protocol allowing email clients to access a remote mail server. It retrieves email messages from a mail server over a TCP/IP connection. This is the same as the POP3 protocol since the IMAP is created as an alternative to POP3. IMAP protocol is designed for the complete management of an email box by multiple email clients. Email messages can stay on the server until you choose to delete them yourself. The protocol listens on port 143, and the secure port over SSL/TLS is port 993, IMAP securely.
There are two types of IMAP servers: Self-managed IMAP servers and Managed IMAP. Self-managed IMAP servers are hosted on hardware or infrastructure owned by the users, where the IMAP protocol is already configured. This is the case when clients have their domains, own VPS servers, and own services at the hosting companies. Unlike the self-managed, the managed IMAP servers are operated by third-party giants like Gmail, Yahoo, Hotmail, etc.
The advantages of using IMAP are that IMAP has seamless email management. It also includes server-side storage, better security, and support for various email clients. Typically this is used with popular clients such as Gmail, Outlook, Thunderbird, and synchronized across devices.
There are not many disadvantages, but there is a higher risk of cyberattacks on the mail. Additionally synchronization of the data is a little bit slower since it is on the server and storage is limited. However, these are minor issues and IMAP is still an optimal protocol for regular use.
Differences Between Email Protocols
We will compare the differences in three different paragraphs, and each paragraph will be the difference between the two protocols. Let’s start first with IMAP and POP3.
IMAP vs POP3
The difference between these protocols is that POP3 downloads the mail locally, while IMAP shows the mail on the server. IMAP stores emails on the server and there is synchronization between the mails. Alternatively, POP3 deletes them from the server, there is no synchronization, or management of the emails. The final difference is that IMAP keeps several copies of the mail, and POP3 doesn’t offer that.
SMTP vs POP3
The main difference between these two protocols is that SMTP is a push protocol and POP3 is a pop protocol. POP3 retrieves and downloads mail locally, while SMTP sends the mail from the sender’s device to the recipient’s inbox. SMTP is between the sender and receiver mail server while POP3 is between the receiver and the receiver’s mail server.
SMTP vs IMAP
The difference between these two protocols is that SMTP is for sending data, and IMAP is for retrieving messages. SMTP is between the servers and for transfer of the data, while IMAP is between the client and server.
You Now Understand Email Protocols
That’s it. You learned the difference between the SMTP, POP3, and IMAP mail protocols.
If you liked this post comparing email protocols, please share it with your friends or leave a comment down below.