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Email Protocols

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Email protocols are a collection of protocols that are used to send and receive emails properly. The email protocols provide the ability for the client to transmit the mail to or from the intended mail server. Email protocols are a set of commands for sharing mails between two computers. Email protocols establish communication between the sender and receiver for the transmission of email. Email forwarding includes components like two computers sending and receiving emails and the mail server. There are three basic types of email protocols.

Types of Email Protocols:

Three basic types of email protocols involved for sending and receiving mails are:

  • SMTP
  • POP3
  • IMAP
Types of Email Protocol


SMTP (Simple Mail Transfer Protocol):

Simple Mail Transfer Protocol is used to send mails over the internet. SMTP is an application layer and connection-oriented protocol. SMTP is efficient and reliable for sending emails. SMTP uses TCP as the transport layer protocol. It handles the sending and receiving of messages between email servers over a TCP/IP network. This protocol along with sending emails also provides the feature of notification for incoming mails. When a sender sends an email then the sender’s mail client sends it to the sender’s mail server and then it is sent to the receiver mail server through SMTP. SMTP commands are used to identify the sender and receiver email addresses along with the message to be sent.

Some of the SMTP commands are HELLO, MAIL FROM, RCPT TO, DATA, QUIT, VERIFY, SIZE, etc. SMTP sends an error message if the mail is not delivered to the receiver hence, reliable protocol.  

For more details please refer to the Simple Mail Transfer Protocol (SMTP) article.

POP(Post Office Protocol):

Post Office Protocol is used to retrieve email for a single client. POP3 version is the current version of POP used. It is an application layer protocol. It allows to access mail offline and thus, needs less internet time. To access the message it has to be downloaded. POP allows only a single mailbox to be created on the mail server. POP does not allow search facilities

Some of the POP commands are LOG IN, STAT, LIST, RETR, DELE, RSET, and QUIT. For more details please refer to the POP Full-Form article.

IMAP(Internet Message Access Protocol):

Internet Message Access Protocol is used to retrieve mails for multiple clients. There are several IMAP versions: IMAP, IMAP2, IMAP3, IMAP4, etc. IMAP is an application layer protocol. IMAP allows to access email without downloading them and also supports email download. The emails are maintained by the remote server. It enables all email operations such as creating, manipulating, delete the email without reading it. IMAP allows you to search emails. It allows multiple mailboxes to be created on multiple mail servers and allows concurrent access. Some of the IMAP commands are: IMAP_LOGIN, CREATE, DELETE, RENAME, SELECT, EXAMINE, and LOGOUT.

For more details please refer to the Internet Message Access Protocol (IMAP) article.

Email Protocols


MIME(Multipurpose Internet Mail Extension Protocol):

Multipurpose Internet Mail Extension Protocol is an additional email protocol that allows non-ASCII data to be sent through SMTP. It allows users to send and receive different types of data like audio, images, videos and other application programs on the Internet. It allows to send multiple attachments with single message. It allows to send message of unlimited length.    

Last Updated : 15 Jun, 2022
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