Email: SMTP, POP and IMAP

Email: Electronic mail is a standard way of transferring files, pictures, document etc. using email service providers such as Gmail, Yahoo, Outlook, etc. For this, there are standard protocols to transfer and receive emails that need to be followed. These protocols are:

1.    Simple message transfer protocols (SMTP).

2.    Post office protocol (POP 3).

3.    Internet message access protocol (IMAP).

 

SMTP: Simple message transfer protocols are responsible for sending emails between email clients (Window mail, thunderbird, etc.) and email the provider (Gmail, outlook, yahoo, etc). By default, there are 3 SMTP protocols:

·      Port 25- This is a default SMTP non-encrypted port.

·      Port 2525 – This port is unofficially used as an alternative to port 25. It is used as a dedicated port for VPN clients or for those who cannot directly send mail to a mail server outside of their internet service provider network because of blocking of port 25.

·      Port 465 -This port is used to send messages using SMTP securely.

Key features of SMTP:

1.    SMTP is application-level protocol.

2.    It is a connection-oriented protocol and text-based protocol.

3.    It handles the exchanges of messages with notification services over the TCP/IP network.

4.    It is a reliable protocol because error report or message not delivered services are also handled by SMTP.

IMAP:  Internet message access protocol is a protocol used to send and receive emails to multiple users at a time. This protocol helps us to read messages even without downloading the file to our local computer. IMAP and POP3 are the two most commonly used Internet mail protocols for sending and retrieving emails. IMAP has two ports. These are:

 

Port 143 – This is a default non-encrypted port.

Port 993 – This port is used to transfer and receive securely.

 

Key features:

1.    You did not require downloading message or file to read.

2.    It enables us to take any action such as downloading, delete the mail without reading the mail.

3.    It enables us to search for emails.

4.    It allows to concurrently access to multiple mailboxes on multiple mail servers.

POP 3: Post office protocol 3 is a standard mail protocol used to receive emails from a remote server. It allows you to download email message on your local computer and read in offline mode. This protocol has two ports. These are:

Port 110 – This is the default non-encrypted port.

Port 995 – This port is used to transfer messages securely.

Key features:

1.    It is application layer internet protocol.

2.    It supports offline access to the message.

3.    It is necessary to download messages.

4.    It allows only one mailbox to be created on the server.

Comparison between POP and IMAP:

S. No.	POP	IMAP
1	It provides support to a single client at a time.	It provides support to multiple clients at a time.
2	Message can be accessed offline i.e. message has to download before accessing.	Message can be accessed online or offline i.e. we can access message without downloading.
3	It doesn't provide a search facility.	It provides a search facility.
4	Only one mailbox can be created.	Multiple mailboxes can be created.
5	The auto downloading facility is not there.	Users can view the heading and sender details before taking any further action.