Working mechanism of e mail

WORKING MECHANISM OF E-MAIL

Faculty of Engineering and Technology

Mahatma Gandhi Chitrakoot Gramodaya Vishwavidhalaya

Chitrakoot Satna (M.P.)

2016-2017

Guided By

Dr. Govind Singh

Presented By

Anamika Singh

B.Tech (I.T.) VII SEM

ROLL.NO. 124503

Content

Introduction

History

Terminology

Architecture

MIME

Web Based E-mail

E-mail Security

Anamika Singh B.Tech (I.T.) VII SEM

Faculty Of Engineering And Technology MGCGV Chitrakoot Satna MP

Working Mechanism of E-Mail

Introduction

Electronic mail commonly called email, is a method of

exchanging digital message from an author to one or more

recipients.

E-mail systems are based on a store & forward model in

which E-mail server systems accepts, forward, deliver and

store messages on behalf of users, who only need to connect

to the e-mail infrastructure.

That was invented before the internet.

As companies began to connect their central system to their

head office then employee were able to send email to other

employee on a world-wide basis.




History

The foundation for today’s global internet e-mail service wascreated in the early ARPANET

Initially, local email program(SNDMSG & READMail) wasinvented by Ray Tomlinson at 1970

In 1978, Shiva Ayyadurai created full scale electronic versionof the inter-office page mail system named as EMAIL.

1988- first commercial product for accessing mail,EUDORA

1999-mail access via mobile phone(Black berry)

2007-Google launch gmail at fool’s day

April 2012, E-mail was registered as a invention of RayTomlinson




Terminology

Mail Box

User Agent (UA)

Message Transfer Agent (MTA)

Message Access Agent (MAA)




User Agent

A User Agent is a software package(program)

It provides services to the user to make the process of

sending and receiving a message easier.

There are 2 types of user agent

• Command-driven:- mail, pine, elm

• GUI-based:- Eudora, Outlook

Sending mail- envelope the message and send

Receiving mail- Informs the user with a notice.




Email address & Message




MTA:SMTP

SMTP stands for Simple Mail Transfer protocol (with TCP

Port Number-25)

S C S SC C

INTERNET

MTA

SMTP

MAA

Mail ServerMail Server

MTA

Sender

SMTP

POP OR IMPA

Receiver




Command and Response




Command And Response(cont.)




MAA:POP or IMAP

POP stands for Post Office Protocol (TCP P.No.-110)

It is simple but Limited in functionality. The client POP3

software is installed on the recipient computer ,the server

POP3 software is installed on the mail server

IMAP stands for Internet Message Access Protocol

It is similar to POP but it has more features.

It is more power full but complex




Difference




Architecture



First Scenario in Electronic Mail

When the sender and the receiver of an e-mail are on

the same system ,we need only two user agents.


Architecture(Contd.)



Second Scenario in Electronic Mail

When the sender and the receiver of an e-mail are on

different systems, we need two UAs and a pair of MTAs

(client and server).





Third Scenario in

Electronic Mail

When the sender is

connected to the mail

server via a LAN or a

WAN, we need two

UAs and two pairs of

MTAs (client and

server).










Fourth Scenario in Electronic Mail

When both sender and receiver are connected to the mail server

via a LAN or a WAN, we need two UAs, two pairs of MTAs and

a pair of MAAs. This is the most common situation today.

MIME


• MIME stands for Multipurpose Internet Mail Extensions

• It is a Supplementary protocol that allow Non-ASCII data and

deliver it to the client MTA to be sent through the internet



MIME (Contd.)




MIME (Contd.)




Web-Based E-Mail

Some websites provide email service to anyone who access

the site. Common sites such as Gmail, Yahoo, Hotmail etc.

Here the transfer of message from sending mail server to the

receiving mail server is still through SMTP.

Instead of POP3 or IMAP4,HTTP is normally used

When receiver wants to retrieve e-mails, he sends a request

HTTP message to the website. the website sends a form which

includes the log-in name and password. If log-in name and

password match, the list of e mail is transferred from the web

server




Concept of layers in E-mail

Firewall- A device(usually a router) installed between the

internal network of an organization and the rest of the internet.

Packet-Filter Firewall:-forward or block packets based on

the source and destination IP and Port address. Example-

Block HTTP (port 80), Block TELNET (port 25) etc.

Proxy firewall:-Filter a message based on the information

available in the message itself. Sometimes called

application Gateway.




Concept of layers in E-mail (Contd.)

Application Layer

For web application:- HTTPS

E-mail Security:- Pretty Good Privacy (PGP )

Secure/Multipurpose Internet Mail Extension (S/MIME)




Message

DigestCompression

Digitally

Signed


Transport Layer

Secure Socket Layer (SSL):- It is designed to provide

security and compression services to data generated from

the application layer.

UDP is not facilitated with this protocol due to connection

establishment.

If server and client are running on SSL programs, then client

can use the URL https://... Instead of http://....

Services:- Fragmentation, Compression, Message Integrity ,

Confidentiality, Framing





Network Layer IP Sec:- IP Security

Authentication Header (AH):- design to authenticate the

source host and to sure the integrity of the payload.

It use Hash function and secret key for Message Digest

Encapsulating Security Payload (ESP):- It provide

Confidentially as well as source authentication and data

integrity.

ESP tailer is added

payload and tailer are encrypted

ESP header is added

All are used to create Authentication data

Add Authentication data at ESP tailer and add IP Header





Data Link Layer Point to Point Protocol (PPP):- It provide a standard way to

transport multiport data over point to point link. New version

of PPP provides connection over multiple links.

PPP uses another set of protocol for link establishment,

authentication

Link Control Protocol (LCP):- for establishing, maintaining,

configure and terminating links.

Password Authentication Protocol (PAP):- Take identification

and password and check the validity

Challenge Handshake Authentication Protocol(CHAP):- 3-

way handshaking authentication protocol





Physical Layer

Transmission Media

Guided Media:- LAN,MAN,WAN, Twisted Pair Cables

Wireless Media:- Wi-Fi ,Bluetooth


