This document discusses the structure and architecture of email. It begins with an introduction and history of email, then describes how an email is composed of a header and message body. It explains that emails are sent and received through a system of user agents, message transfer agents, and message access agents. User agents allow users to compose and read emails, while message transfer agents use SMTP to transfer emails across networks, and message access agents pull emails from servers using protocols like POP3 and IMAP.

1. Presented By:-
Bhojak Rajendra

2.  Introduction
 History of E-mail
 Comparison With Postal Mail
 Uses of E-mail
 Structure of E-mail
 Architecture of E-mail
 User agent Message Transfer agent
 Message Access agent

3.  Electronic mail, often abbreviated as E-mail,
is a method of exchanging digital messages,
designed primarily for human use.
 E-mail systems are based on a store &
forward model in which E-mail server
systems accept, forward, deliver and store
messages on behalf of users, who only need
to connect to the e-mail infrastructure.

4.  The foundation for today's global Internet e-
mail service was created in the early
ARPANET
 Standards for encoding of messages were
proposed as early as, for example, in 1973
(RFC 561).
 An e-mail sent in the early 1970s looked very
similar to one sent on the Internet today.
 Network-based email was initially exchanged
on the ARPANET in extensions to the (FTP),
but is today carried by the (SMTP).

5. To:-(Address)
From:-
(Address)
Subject:-any
Dear...
(message)
Your
faithfully:-
...........
Abc @gmail.com
To
Xyz @gmail.com
From:-abc
To:-Xyz
Date:-...........
Subject:-Any
Dear......
(message)
Your faithfully:-
ENVELOPE
Header
Body
Message

6.  We can send a message anytime anywhere.
 We can send the same message to several
peoples at same time.
 We can forward the information to co-
workers without retyping it.
 We can send the messages around the world
as easily as to friend in the next cabin .

7.  We can save the time, E-mail is very fast,
usually taking no more time than a few
minutes to be received.
 We can mail Electronic documents and
recipients can then edit and return revised
versions.
 It is very fast as compare to postal mail.

8.  An electronic mail message consists of two
components
 Message header:-The message header contains
control information, including an originators email
address and one or more recipient addresses.
Usually additional information is added, such as a
subject header field.
 Message body:- which is the emails content.

9.  The message header should include at least the
following fields:
 From :-The e-m addresses, and optionally the
name of the : ail author or sender.
 To:- The e-mail address of the messages
recipient(s). Indicates primary recipients
(multiple allowed), for secondary recipients see
Cc: and Bcc.
 Bcc:- Blind carbon copy addresses added to the
SMTP ; delivery list but not (usually) listed in the
message data, remaining invisible to other
recipients.
 Cc: -Carbon copy Many e-mail clients will mark
e-mail in ; your inbox differently depending on
whether you are in the To:- or Cc:

10.  Date:- The local time and date when the
message was written, automatically attached
while sending.
 Subject:- A brief summary of the topic of
the message.
 Message-ID:- Also an automatically
generated field; used to prevent multiple
delivery .
 Attachment:- Attachment contain the name
of files . That you want to send. example a
world document.

11.  To deliver mail ,a system must use an
addressing system with unique addresses
 Address consist two parts :-
1. Local part
2. Domain name
 These are separated by @ sign.

12.  Like a postal address ,an email address
specifies the destination of electronic
message.
 An internet Email address look like this
Ex:-User name @domain name
 The user name is a unique name that
identified the recipient.
 The domain name in the address.
 many people can share the same
domain name.

13.  The first component of E-mail is user
agent(UA).
 It provide the services to user to make the
process of sending & receiving a message
easier.
 A UA is a software package(Program) that
composes, read, replies to and forward
messages.
 It also handles the Mailboxes.

14. User Agent
Reading
Message
Composing
Message
Handling
Message
Forwarding
Message
Replying
Message

15. MME(Multiplurpose Internet Mail
Extension) Protocol

16.  The actual mail transfer is done through
MTA.
 To send mail , a system must have client
MTA.
 To receive mail ,a system must have
server MTA. The protocol that define the
MTA client & server in the internet is
called SMTP (simple mail transfer
protocols).
 SMTP define how commands & response
must be sent back & forth.

17.  The first and the second stages of mail
delivery use SMTP.
 SMTP is a PUSH protocols.
 On the other hand, the third stage needs
a pull protocol ; the client must pull
messages from the server . The direction
of the bulk data is from the server to the
client . At this stage Message Access Agent
is use.
 SMTP SMTP MAA Receiver Sender LAN or
WAN LAN or WAN Mail server INTERNET

19.  UA prepares the messages, creates the
envelopes, and puts the message in the
envelope.
 Mail address is like Xyz@domainname.
 Multipurpose Internet Mail Extensions (MIME)
allows the transfer of multimedia messages.
 MTA transfer the mail across internet, a LAN
or a WAN.

20.  SMTP uses commands and responses to the
transfer messages between an MTA client and
MTA server.
 Post Office Protocol, Version 3 (POP 3) and
Internet Mail Access Protocol.
 Version 4 (IMAP 4) are used for pulling
messages from a mail server.

21.  Data communications and networking by
Behrouz A.Forouzan (4th edition).
 http:/en.wikipedia.org/wiki/E-mail.
 Computer Networks, by A.S. Tanenbaum
 (4th Ed.)