What two protocols are used to deliver mail messages

Electronic mail Protocols

E-mail Protocols are ready of rules that help the client to properly transmit the information to or from the mail service server. Here in this tutorial, nosotros will hash out various protocols such as SMTP, Popular, and IMAP.

SMPTP

SMTP stands for Simple Mail service Transfer Protocol. It was first proposed in 1982. It is a standard protocol used for sending e-mail efficiently and reliably over the internet.

Key Points:

SMTP is application level protocol.
SMTP is connection oriented protocol.
SMTP is text based protocol.
It handles exchange of messages betwixt electronic mail servers over TCP/IP network.
Apart from transferring email, SMPT likewise provides notification regarding incoming mail service.
When y'all send electronic mail, your email client sends it to your eastward-mail service server which further contacts the recipient mail server using SMTP customer.
These SMTP commands specify the sender's and receiver's e-mail accost, forth with the message to be transport.
The exchange of commands between servers is carried out without intervention of whatever user.
In example, message cannot be delivered, an error study is sent to the sender which makes SMTP a reliable protocol.

SMTP Commands

The following table describes some of the SMTP commands:

South.N.	Command Description
i	HELLO This command initiates the SMTP conversation.
2	EHELLO This is an culling control to initiate the chat. ESMTP indicates that the sender server wants to utilize extended SMTP protocol.
3	Mail service FROM This indicates the sender'south address.
4	RCPT TO Information technology identifies the recipient of the mail. In order to deliver similar message to multiple users this command tin can be repeated multiple times.
5	SIZE This command let the server know the size of fastened message in bytes.
6	Data The DATA command signifies that a stream of data volition follow. Here stream of data refers to the body of the message.
7	QUIT This commands is used to terminate the SMTP connection.
8	VERFY This command is used by the receiving server in order to verify whether the given username is valid or not.
9	EXPN It is aforementioned as VRFY, except it volition list all the users proper noun when it used with a distribution list.

IMAP

IMAP stands for Internet Message Admission Protocol. It was beginning proposed in 1986. There be five versions of IMAP as follows:

Original IMAP
IMAP2
IMAP3
IMAP2bis
IMAP4

Key Points:

IMAP allows the client program to dispense the e-mail message on the server without downloading them on the local computer.
The e-mail is hold and maintained by the remote server.
It enables us to accept any action such equally downloading, delete the post without reading the postal service.It enables united states to create, manipulate and delete remote bulletin folders called mail boxes.
IMAP enables the users to search the e-mails.
It allows concurrent access to multiple mailboxes on multiple mail servers.

IMAP Commands

The following table describes some of the IMAP commands:

S.N.	Control Description
1	IMAP_LOGIN This control opens the connection.
2	CAPABILITY This control requests for listing the capabilities that the server supports.
3	NOOP This control is used as a periodic poll for new messages or message status updates during a period of inactivity.
4	SELECT This command helps to select a mailbox to access the messages.
5	EXAMINE It is same as SELECT control except no alter to the mailbox is permitted.
6	CREATE Information technology is used to create mailbox with a specified name.
7	DELETE Information technology is used to permanently delete a mailbox with a given name.
viii	RENAME It is used to alter the proper name of a mailbox.
9	LOGOUT This command informs the server that client is washed with the session. The server must transport BYE untagged response before the OK response and then shut the network connection.

POP

Popular stands for Post Office Protocol. It is generally used to support a unmarried client. There are several versions of Popular but the POP 3 is the current standard.

Key Points

Popular is an application layer internet standard protocol.
Since Pop supports offline admission to the messages, thus requires less net usage time.
POP does not allow search facility.
In order to access the messaged, it is necessary to download them.
Information technology allows simply i mailbox to be created on server.
It is not suitable for accessing non mail information.
POP commands are generally abbreviated into codes of 3 or iv letters. Eg. STAT.

Popular Commands

The post-obit table describes some of the POP commands:

S.N.	Command Clarification
one	LOGIN This command opens the connexion.
ii	STAT It is used to display number of messages currently in the mailbox.
3	LIST It is used to go the summary of messages where each message summary is shown.
4	RETR This command helps to select a mailbox to admission the messages.
5	DELE It is used to delete a message.
6	RSET It is used to reset the session to its initial state.
7	QUIT It is used to log off the session.

Comparing between Pop and IMAP

S.Due north.	Pop	IMAP
ane	Generally used to support unmarried customer.	Designed to handle multiple clients.
2	Messages are accessed offline.	Messages are accessed online although it also supports offline style.
iii	Pop does non allow search facility.	Information technology offers power to search emails.
4	All the messages have to be downloaded.	Information technology allows selective transfer of messages to the client.
five	Simply ane mailbox can be created on the server.	Multiple mailboxes can be created on the server.
half dozen	Not suitable for accessing non-mail information.	Suitable for accessing non-mail information i.east. zipper.
7	Popular commands are generally abbreviated into codes of 3 or four letters. Eg. STAT.	IMAP commands are not abbreviated, they are total. Eg. Status.
eight	Information technology requires minimum utilize of server resource.	Clients are totally dependent on server.
9	Mails once downloaded cannot exist accessed from some other location.	Allows mails to be accessed from multiple locations.
ten	The e-mails are not downloaded automatically.	Users can view the headings and sender of eastward-mails and then decide to download.
ten	POP requires less internet usage time.	IMAP requires more than cyberspace usage time.