MINISTRY OF SCIENCE AND ENGINEERING

TECHNOLOGICAL UNIVERSITY THANLYIN

DEPARTMENT OF ELECTRONIC ENGINEERING

Electronic Mail In The Internet

Presented by 21-1-2025
Group - 8 1
 List of members

No Name Roll No

1. Ma Mya Nandar Win VIEC- 58

2. Ma Wint Myat Phyo VIEC- 59

3. Ma Thet Htar Shwe Zin VIEC- 60

4. Mg Phyo Ko Ko VIEC- 64

5. Ma May Myat San VIEC- 65

6. Ma Pa Pa Linn VIEC- 66

7. Ma Phoo Moh Moh Zaw VIEC- 67

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Introduction
o A system for exchanging digital messages over the Internet, including
sender/recipient addresses, subject, body, and attachments.
o Protocols involved: SMTP (sending), POP3, and IMAP (retrieving and managing).
o Instant global communication.
o Sends text and multimedia files.
o Vital for personal, academic, and business use.
o Used for communication with friends, family, colleagues, and in business, marketing,
and customer support.
o Facilitates communication in academia and government settings.
o Mail Box, and Spool file. These are explained as following below.
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Three Major Components Of Email

o User agents
o Mail servers
o Simple mail transfer protocol:
SMTP

Figure 1. Three components of email

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User agents

o A mail user agent (MUA), also called an mail User

reader is a mail client application Agents
o Users access to a mail server in order to create,
send, and receive email messages.
o MUA examples include Microsoft Outlook,
Gmail, and Apple Mail…etc.
o Outgoing, incoming messages stored on server
Figure 2. User agents

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Mail Server

o A mail server facilitates sending, receiving, and Mail

Server
storing emails.
o Acts as a central hub between email clients and the
internet.
o Processes and delivers incoming emails, relays
outgoing messages.
o Includes Mail Transfer Agents (MTA) and Mail
Delivery Agents (MDA).
o Essential for email communication between users
and mail clients. Figure 3. Mail Server

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SMTP

o SMTP stands for Simple Mail Transfer Protocol.

o It is used to send emails between mail servers.
o Works with Mail Transfer Agents (MTA) to
route emails.
o Ensures reliable and efficient email delivery.
o SMTP requires message (header & body) to be
in 7-bit ASCII
o SMTP server uses CRLF.CRLF to determine end
of message

Figure 4. SMTP
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 “client” “server”
SMTP RFC (5321) SMTP server SMTP server

o Uses TCP to reliably transfer email message

from client (mail server initiating connection) to initiate TCP
connection
server, port 25 RTT
 direct transfer: sending server (acting like client) to TCP connection
receiving server initiated

o Three phases of transfer 220

• SMTP handshaking (greeting) SMTP HELO
handshaking
• SMTP transfer of messages
250 Hello
• SMTP closure
o Command/response interaction (like HTTP)
SMTP
• commands: ASCII text transfers
• response: status code and phrase time
Figure 5.SMTP RFC (5321) 8
Scenario: Alice sends e-mail to Bob
1. Alice uses UA to compose e-mail 4.SMTP client sends Alice’s message
message “to” bob@someschool.edu over the TCP connection
2. Alice’s UA sends message to her mail 5.Bob’s mail server places the message
server using SMTP; message placed in in Bob’s mailbox
message queue
3. Client side of SMTP at mail server 6. Bob invokes his user agent to read
opens TCP connection with Bob’s mail message
server

Figure 6. Scenario: Alice sends e-mail to Bob 9

Comparison with HTTP
HTTP SMTP
HTTP stands for Hypertext transfer protocol. SMTP stands for simple mail transfer protocol.
HTTP is used for data and file transfer SMTP is used for mail services.
HTTP uses port no 80 SMTP uses port no 25.
HTTP uses TCP connection as Persistent and non-
SMTP uses persistent TCP connection only.
persistent
HTTP transfers files and data |information from a SMTP uses mail servers to transfer emails from one
web server to web clients inbox to another.
HTTP uses the Pull protocol SMTP uses push protocol.
HTTP uses band type in-band SMTP uses band type in-band.
SMTP requires 7-bit ASCII [American Standard
HTTP does not require 7-bit ASCII
Code of Information and interchange].
“telnet HTTP server” command is used to interact
“telnet SMTP server” is used in SMTP.
with them in HTTP
HTTP encapsulates each object in its own HTTP SMTP places all of the message’s objects into one
response message message. 10
Mail Message Format
SMTP: protocol for exchanging e-mail messages, defined in RFC 5321 (like RFC 7231
defines HTTP)
RFC 2822 defines syntax for e-mail message itself (like HTML defines syntax for web
documents)

 header lines, e.g., header

• To: blank
• From: line
• Subject:
these lines, within the body of the email body
message area different from SMTP MAIL
FROM:, RCPT TO: commands!
 Body: the “message” , ASCII characters only
Figure 7. Mail Message Format 11
Retrieving email: mail access protocols

user
e-mail access user
SMTP SMTP protocol
agent agent
(e.g., IMAP,
HTTP)

sender’s e-mail receiver’s e-mail

server server
Figure 8. Mail access protocols
o SMTP: delivery/storage of e-mail messages to receiver’s server
o Mail access protocol: retrieval from server
• IMAP: Internet Mail Access Protocol [RFC 3501]: messages stored on server, IMAP
provides retrieval, deletion, folders of stored messages on server
o HTTP: gmail, Hotmail, Yahoo!Mail, etc. provides web-based interface on top of STMP
(to send), IMAP (or POP) to retrieve e-mail messages
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Thank you
for your attention!

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