INTODUCTION:-
Electronic Mail:
Electronic mail (E-mail) is an electronic message transmitted over a
network from one user to another. E-mail is a text-based mail
consisting of lines of text, and can include attachment such as audio
messages, pictures and documents. The features of e-mail are as
follows:
E-mail can be sent to one person or more than one person at
the same time.
Communicating via e-mail does not require physical presence
of the recipient. The recipient can open the e-mail at his/her
convenience.
Since messages are transmitted electronically; e-mail is a fast
way to communicate with the people in your office or to people
located in a distant country, as compared to postal system.
E-mail messages can be sent at any time of the day.
A copy of e-mail message that the sender has sent is available
on the sender’s computer for later reference.
In addition to sending messages, e-mails an ideal method for sending
documents already on the computer, as attachments. E-mail has
features of the regular postal service. The sender of e-mail gets the
e-mail address of the recipient, composes the message and sends it.
The recipient of e-mail can read the mail, forward it or reply back.
The recipient can also store the e-mail or delete it.
E-mail Address:
To use e-mail, a user must have an e-mail address. The e-mail
address contains all information required to send or receive a
message from anywhere in the world. An e-mail address consists of
two parts separated by @ symbol (spelled as at)-the first part is
user_name and the second part is host computer name. The e-mail
address may look like abcdgoel@gmail.com where, abcdgoel is the
user_name, gmail.com is the host computer name (domain name)
i.e. the mailbox where finally the mail will be delivered. Gmail is the
mail server where the mailbox “abcdgoel” exists.
E-mail Message Format:
The e-mail message consists of two parts-header and body. The
header contains information about the messages, such as-
From-Sender’s e-mail address.
To-Recipient’s e-mail address.
Date-When the e-mail was sent.
Subject-The topic of the messages.
Cc-Addresses where carbon copies of the same e-mail will be
sent. The recipients of e-mail can see all e-mail address to
which the copies have been sent.
Bcc-Addresses where Blind carbon copies (Bcc) of the same e-
mail will be sent. The recipients of e-mail do not know that the
same e-mail has been sent to other e-mail addresses.
The size of e-mail.
The body contains the text of the message and any
attachments to be sent.
Step-by-Step Processing of Emailing:
1. Composing the Email
The user writes an email using an email client (like Gmail,
Outlook, or Thunderbird). The messages includes:
Sender’s address (From)
Recipient’s address (To, Cc, Bcc)
Subject line
Body text
Attachments (optional)
2. Clicking Send
When the user clicks “send,” the email client formats the email
using the MIME (Multipurpose Internet Mail Extension) protocol,
which allows for text, images, and attachments.
3. Client contracts SMTP server
The email client contacts the SMTP (Simple Mail Transfer
Protocol) server associated with the sender’s domain. SMPT is
the protocol used to send emails across the Internet.
4. SMPT Server Processing
The SMPT server checks the sender’s identity
It breaks the recipient’s email address into two parts:
username and domain (e.g., user@example.com).
It looks up the recipient’s domain to find its mail server
using DNS (Domain Name System).
5. DNS Lookup and MX Records
The SMPT server queries a DNS server to get the MX (Mail
Exchange) records of the recipient’s domain.
MX records point to the IP address of the recipient’s mail
server.
6. Routing the Email
The SMPT server sends the email to the recipient’s mail
server (also using SMPT).
If the recipient’s server is unreachable, the message is
queued and delivery is retired later.
7. Receiving Mail Server Stores the Email
The recipient’s mail server receives the email and stores it
in the user’s mailbox.
Anti-spam and virus checks may be performed.
8. Recipient Accesses the Email
The recipient uses an email client or webmail to access the
mailbox.
The client connects to the mail server using either.
POP3 (Post Office Protocol 3) – downloads emails and
deletes them from the server.
IMAP (Internet Message Access Protocol) – keeps emails on
the server and synchronizes across devices.
9. Email Displayed to Recipient
The Email client retrieves and displays the message to the user
including all formatting and attachments.
Email Services:
There are two kinds of e-mail services- Application-based e-mail, and
web-based e-mail.
Application-based e-mail is installed onto the user’s computer. The
mail is stored on the user’s computer. For using an application based
e-mail, the user uses a program such as Microsoft Outlook, Outlook
Express etc. The user must have an e-mail account on the Internet
mail server with a domain name (e.g. vsnl.com), which is provided by
the ISP whose services the user is using to connect to the internet.
The user also has an e-mail address (create e-mail address by adding
your username to e-mail server’s domain name E.g.
aagoel@vsnl.com), which indentifies the user uniquely on the e-mail
server. Web-based e-mail or webmail appears in a web browser’s
window. A web-based e-mail can be accessed by the user from any
Internet-connected computer anywhere in the world. Web-based e-
mail is not stored on the user’s computer. Many free web-based e-
mail services are available.
Hotmail, yahoo, and Gmail provide free e-mail accounts. An example
of web-based e-mail address is ashima1234@gmail.com.
How E-mail Works:
The e-mail works on the client-server model. El-mail clients are the
users who wish to use the e-mail facility. The basic functionality of
the client includes-create new e-mail, display and store received e-
mails, address list of contacts etc. Both, the sender of e-mail and the
recipient of e-mail are e-mail clients. E-mail server is a combination
of processes running on a server with a large storage capacity-a list
of users and rules, and the capability to receive, send, and store
emails and attachments.
These servers are designed to operate without constant user
intervention.
The e-mail client interacts with the e-mail server to send or receive
e-mail. Most email servers provide email services by running two
separate processes on the (POP3) and Simple Mail Transfer Protocol
3 (SMTP). Some e-mail servers also run another process on the
machines-Internet Message Access Protocol (IMAP).
SMTP is used to send e-mail from the client to server and from one
server to another server. POP3 is used by client from application
based e-mail to access mail from the server
IMAP is used by client for web-based e-mail to access mail on server.
The e-mail client-server work as follows:
The client connects to e-mail server when the user wants
to send, check or receive e0-mail. The clients connects to
the server on two TCP/IP ports-(1) SMTP on port 25, and
(2) POP3 on port 110 or IMAP on port 143.
SMPT server accepts outgoing email from client (sender e-
mail client). Next, the SMPT server checks the e-mail
address at which e-mail has to be delivered (recipient e-
mail client). If the recipient e-mail client resides on the
same SMPT server, then the e-mail is sent to the local
POP or IMAP server, otherwise, the e-mail is sent to
another SMPT server so that it reaches the recipient e-
mail client’s SMPT server.
POP3 stores e-mail for a client on a remote server. When
the client gets connected to server, the e-mail messages
are downloaded from POP3 server to client’s computer.
IMAP also stores e-mail on a remote server. However, the
e-mail messages are not downloaded to the client’s
computer. The user manipulates the e-mail messages
directly on the e-mail server.
The POP3/IMAP and SMTP are linked by an internal mail
delivery mechanism that moves mail between the
POP3/IMAP and SMTP servers.
HTML (HyperText Markup Language)
1. Introduction
HTML is the standard language used to create and design web pages.
2. Basic HTML Structure
<!DOCTYPE html>
<html>
<head>
<title>My First Web Page</title>
</head><body>
<h1>Welcome to My Website</h1>
<p>This is my first HTML webpage.</p>
</body>
</html>
3. HTML Elements
Headings: <h1> to <h6>
Paragraphs: <p>
Links: <a href=”URL”> Click Here</a>
Images: <img src=”image.jpg”alt=”Description”>
Lists: Orderd <ol> and Unordered <ul>
Concept of HTML (Hypertext Markup
Language)
1.Introduction
HTML stands for HyperText Markup Language. It is the standard
language used to create and design web pages. HTML describes
the structure and layout of a web page using a system of
elements called “tags”.
2.What is HyperText?
HyperText refers to text that contains links to other texts or
resources. Clicking on hyperlink in a webpage redirects the user
to another page or section.
3.Markup Language
A markup language uses tags to define elements within a
document. These tags tell the browser how to display the
content (link heading, paragraphs, images, and links).
4. Structure of an HTML Documents A basis HTML
documents consists of the following parts:
<!DOCTYPE html>
<html>
<head>
<title> Page Title</title>
</head>
<body>
<h1>Main Heading</h1>
<p>This is a paragraph.</p>
</body>
</html>
<!DOCTYPE html>: Declares the HTML version.
<html>: Root element of an HTML page.
<head>: Contains meta-information (e.g., title, styles).
<body>: Contains the visible content of the webpage.
5. Common HTML Tags and Their use
<h1> to <h6>: Headings
<p>: Paragraph
<a>: Hyperlink
<img>: Image
<ul>, <ol>, <li>: Lists
<table>,<span>: Tables
<div>, <span>: Layout and styling
6. Features of HTML
Platform-independent: Runs on any device/browser
Easy to learn and use
Supported by all modern web browsers
Works with CSS and JavaScript for styling and interactivity
7. Importance of HTML
Forms the backbone of all websites
Enables linking and navigation on the internet
8. Limitations of HTML
Not a programming language; cannot perform logic
Static by itself (needs CSS/Js for styling and behaviour)
