E-mail Protocols

E-mail Protocols

E-mail Protocols are set of rules that help the client to properly transmit the information to or from the mail server. Here in this tutorial, we will discuss various protocols such as SMTP, POP, and IMAP.

SMTP

SMTP stands for Simple Mail 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 between e-mail servers over TCP/IP network.
• Apart from transferring e-mail, SMPT also provides notification regarding incoming mail.
• When you send e-mail, your e-mail client sends it to your e-mail server which further contacts the recipient mail server using SMTP client.
• These SMTP commands specify the sender’s and receiver’s e-mail address, along with the message to be send.
• The exchange of commands between servers is carried out without intervention of any user.
• In case, message cannot be delivered, an error report is sent to the sender which makes SMTP a reliable protocol.

IMAP

IMAP stands for Internet Mail Access Protocol. It was first proposed in 1986. There exist five versions of IMAP as follows:

1. Original IMAP
2. IMAP2
3. IMAP3
4. IMAP2bis
5. IMAP4

Key Points:

• IMAP allows the client program to manipulate 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 take any action such as downloading, delete the mail without reading the mail.It enables us to create, manipulate and delete remote message folders called mail boxes.
• IMAP enables the users to search the e-mails.
• It allows concurrent access to multiple mailboxes on multiple mail servers.

POP

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

Key Points

• POP is an application layer internet standard protocol.
• Since POP supports offline access to the messages, thus requires less internet usage time.
• POP does not allow search facility.
• In order to access the messaged, it is necessary to download them.
• It allows only one mailbox to be created on server.
• It is not suitable for accessing non mail data.
• POP commands are generally abbreviated into codes of three or four letters. Eg. STAT.

Comparison between POP and IMAP

S.N.	POP	IMAP
1	Generally used to support single client.	Designed to handle multiple clients.
2	Messages are accessed offline.	Messages are accessed online although it also supports offline mode.
3	POP does not allow search facility.	It offers ability to search emails.
4	All the messages have to be downloaded.	It allows selective transfer of messages to the client.
5	Only one mailbox can be created on the server.	Multiple mailboxes can be created on the server.
6	Not suitable for accessing non-mail data.	Suitable for accessing non-mail data i.e. attachment.
7	POP commands are generally abbreviated into codes of three or four letters. Eg. STAT.	IMAP commands are not abbreviated, they are full. Eg. STATUS.
8	It requires minimum use of server resources.	Clients are totally dependent on server.
9	Mails once downloaded cannot be accessed from some other location.	Allows mails to be accessed from multiple locations.
10	The e-mails are not downloaded automatically.	Users can view the headings and sender of e-mails and then decide to download.
10	POP requires less internet usage time.	IMAP requires more internet usage time.