Email Communication

What is Email?
 Full Form: Electronic Mail
 Definition: A method of sending digital messages (text, images, multimedia) from one
device to another using the Internet.
 Introduced by: Ray Tomlinson in 1971 (first used “@” to separate user and host).
 First Email: Sent in 1965 using MIT’s mailbox program for same-computer
communication; ARPANET (Advanced Research Projects Agency Network) enabled
inter-computer email in the early 1970s.
 Inventor (Confusion in sources): Ray Tomlinson is credited for actual email as we use
today (using @), while early mailbox programs were used before for local messaging.

Origin and History of Email

1. ARPANET Era (1960s-1970s):
o Developed by U.S. Department of Defense’s ARPA for computer networking.
o Early experiments of sending messages between computers.
2. 1971 – Ray Tomlinson:
o Introduced the “@” symbol to denote sending from user@host.
o Became a standard email format worldwide.
3. 1973 Onwards:
o Majority of ARPANET traffic became electronic messages.
o Protocols for email sending/receiving were developed.
4. Late 1970s – 1980s:
o Features introduced: Cc (Carbon Copy), Bcc (Blind Carbon Copy), file
attachments.
5. 1990s – Rise of Commercial Email Providers:
o Yahoo! Mail, Hotmail emerged as free webmail services.
o Email became accessible to the public globally.
6. Today:
o Integral for personal, academic, business, and government communication.
o Accessible via smartphones, desktops, tablets with 24/7 connectivity.
Types of Email Services

Email services vary based on provider type and their terms and conditions.

Free Web-based Email Services

 Definition: Accessible via web browsers like Internet Explorer, Firefox, etc.
 Protocol Used: Generally uses HTTP; for secure login uses HTTP (e.g.
https://gmail.com).
 Examples:

 Gmail (username@gmail.com)
 Outlook (username@outlook.com)
 Yahoo! Mail (username@yahoo.com)
 ProtonMail (username@protonmail.com)
 Zoho (username@zoho.com)
 AOL (username@aol.com)

 Funding: Free for users; funded by advertisements shown to account holders.

 Terms: Users must accept terms and conditions before signing up.
 Features:
o Spam filtration.
o Virus scanning.
o Secure login with HTTPS.

Priced Web-based Email Services

 Definition: Premium email services offered on payment basis.

 Examples: Paid versions of Yahoo! and Hotmail.
 Advantages:
o More secure communication.
o Better spam filtration.
o Increased storage space.
 Usage: Mostly for business communication and professional use.
Private Email Services

 Definition: Email accounts provided by organizations/institutions to their members.

 Features:
o Dedicated mail server of the institution.
o Free for staff and members.
o Valid only till membership exists.
 Examples:
o abc@ugc.ac.in, abc@satyam.net

Components of an Email

Component Description

The title of the email, indicating its content. Determines if recipient

Subject Line
opens it.

Body Main message text, sharing information or asking questions.

Files (documents, images, spreadsheets) sent along with the email

Attachments
to supplement content.
Sender’s name, designation, contact info, company logo, or
Signature
personal quotes.

CC (Carbon Copy) Sending a copy to additional recipients visible to all.

BCC (Blind Carbon

Sending a copy to hidden recipients (others cannot see).
Copy)

Email Structure and Format

Three parts of Email Format:

1. Message Envelope: Routing information (sender, recipient details, not visible to user
directly).
2. Message Header: To, From, Subject, Date, Cc, Bcc.
3. Message Body: Main content/text of the email.

Example of Email Address: scholarify@gmail.com

 Username: scholarify
 @ sign
  Domain name: gmail.com

Email Folders and Interface

Folder Purpose

Inbox Stores received emails.

Sent Items Stores emails that have been sent.

Deleted Items / Trash Stores deleted emails temporarily.

Draft Folder Stores composed but unsent emails.

Stores unsolicited or suspicious emails.
Spam / Junk
unwanted email advertisements
Compose Mail Used to write and send new emails.

Folder Pane: Usually on the left side of email window showing above folders.

Spoofing: A method of spamming where the spammer uses false email address which does not
exist.

Important Email Protocols

POP (Post Office Protocol)

 Type: Supports offline email management.

 How it works:
o Email client connects to mail server.
o Retrieves all messages and stores them locally.
o Marks them as new/unread.
o Deletes messages from server after download.
 Usage: Mostly by Internet Service Providers (ISPs) for personal emails.

IMAP (Internet Message Access Protocol)

 Type: Supports both online and offline email management.

  How it works:
o Retrieves only message headers initially.
o Stores local copies in temporary cache.
o Messages remain on server until deleted by user.
 Advantages:
o Multiple email clients can access the same mailbox.
 Usage: Common for corporate/business emails (e.g. sales@company.com).

Protocols Used in Email

SMTP (Simple Mail Transfer Protocol)

 Function: Used to send emails.

 By: Mail Transfer Agent (MTA) to deliver emails to recipient’s mail server.
 Limitation: Cannot receive emails, only for sending.
 Usage: Majority of mail servers use SMTP.

HTTP Protocol

 Function: General web protocol, but used to access mailbox via browser.
 Usage: Compose or retrieve emails from webmail services.
 Examples: Hotmail, Yahoo Mail use HTTP for email access.

Delivery Agents

Mail Transfer Agent (MTA)

 Definition: Software that transfers emails from one host to another (mail server).
 Function:
o Forwards messages to other machines using SMTP.
o Adds Received stamp in email header.
o Delivers mail to recipient’s server or forwards to next host if recipient not present
locally.
 Examples: qmail, sendmail, postfix.

Mail Delivery Agent (MDA)

 Definition: Software used by MTA to deliver email to user’s mailbox.

 Function: Places received mail into target user’s mailbox locally.
  Examples: binmail, delivermail, maildrop, postfix-maildrop.

Access Client

 Definition: Application software acting as a client to access email accounts from

servers.
 Examples:
o Outlook Express
o Outlook
o Thunderbird

Protocol Full Form Function Port

Simple Mail Transfer Sending emails from client to server or
SMTP 25
Protocol between servers
Downloads emails to local device, deletes
POP3 Post Office Protocol version 3 110
from server
Internet Message Access Synchronises and stores emails on server,
IMAP 143
Protocol access from multiple devices
Secure Multipurpose Internet
S/MIME Email encryption and security standard –
Mail Extension

Domain Names Used in Email

Domain Usage
.com Commercial
.edu Educational institutions
.gov U.S. Government
.int International organizations
.mil U.S. Military
.net Network providers
.org Non-profit organizations

Advantages of Email
 Free of cost
 Fast and global communication
 Can send multimedia files easily
 Environment friendly (no paper)
  Accessible from multiple devices

Disadvantages of Email
 Long notes take time to read and reply
 Important emails may get missed among many
 Spam/junk emails pile up
 Wrong email address can send to unintended recipients
 Viruses and phishing risks via attachments

Types of Email Attacks

Types of Email Attacks

Phishing Attack

 Cybercriminal sends a fake email that looks like it’s from your bank or some trusted
company.
 They try to get your password, ATM PIN, or credit card number.

Example: "Your SBI account will be blocked. Click here to confirm details." — this email
actually doesn’t come from the bank.

Spear Phishing

 This is a more dangerous form of phishing — in which the email is made for a specific
person or company.

Example: An email comes to HR in the name of the CEO: "Urgent: Transfer 5 lakhs to this
new account."

Whaling

 Phishing attacks targeting big officers or CEOs.

 Example: An email comes to the CEO which looks like it’s from their boss — "Send
company sales report immediately.

BEC – Business Email Compromise

 Attacker copies someone from inside the company so they can take money or steal
important information.

Example: Email comes — "This is your supplier, our bank details have changed. Please send
payment here."

Ransomware Attack

 A file is sent through email — opening it locks all your data. Then money is
demanded to decrypt it.

Example: An email with "Attached invoice" installs ransomware.

Malware Distribution

 The email has an attachment or link that installs a virus.

Example: An email comes — "Holiday Photos.zip" — but the zip file has a virus.

Man-in-the-Email Attack

 Attacker silently intercepts an ongoing email conversation between two people and
edits the message before forwarding it.

Example: The attacker changes payment details, and the money goes into the wrong account.
Domain Spoofing

 Email looks like it’s from a real company but has a small fake change.

Example: Email comes: support@amaz0n.com (where “0” is written instead of real “o”).

Email Bombing

 Thousands of emails are sent to your inbox at the same time — so the system becomes
slow or crashes.

Example: 10,000 emails come in just 5 minutes.

Graymail

 Emails that are newsletters or offers — not malicious, but unwanted.

Example: "50% Off! New Deals for You" — sale emails that come daily.
 Attack Type Description Example

Impersonating legitimate Fake bank email asking to confirm

Phishing
entities to steal info account details
Targeted phishing for specific Fake email from CEO asking to
Spear Phishing
individuals transfer funds
Email deceiving a CEO for
Whaling Targeting senior executives
sensitive data
Business Email Impersonating company staff Fake supplier asking payment to
Compromise (BEC) for unauthorized transfers new account
Malicious software encrypts Invoice email installing ransom
Ransom ware
data demanding ransom ware when opened
Emails with harmful software “Holiday photos” email installing
Malware Distribution
attachments virus
Man-in-the-Email Intercepts and alters email Changes payment details in
Attack content ongoing business deal
Fake domains similar to real support@amaz0n.com instead of
Domain Spoofing
ones support@amazon.com
Flooding inbox with massive Inbox flooded with thousands of
Email Bombing
emails nonsensical emails
Unwanted but not malicious Continuous promotions from old
Graymail
emails subscriptions

Important Abbreviations

Abbreviation Meaning

Email Electronic Mail

CC Carbon Copy
BCC Blind Carbon Copy
IMAP Internet Message Access Protocol
SMTP Simple Mail Transfer Protocol
POP3 Post Office Protocol version 3
S/MIME Secure Multipurpose Internet Mail Extension
 Most Important Email-Based Viruses and Attacks Till 2025

Virus/Attack
# Year(s) Type How it Spread via Email Impact/Importance
Name

Infected Word docs sent via First major email virus;

1 Melissa 1999 Email Worm
Outlook overloaded mail servers

.vbs file disguised as "Love ~$10B in damages; most famous

2 ILOVEYOU 2000 Email Worm
Letter" email virus

2001– Spoofed sender; random Disabled antivirus, faked

3 Klez Email Worm
2002 attachments senders, very widespread

Fake email delivery errors with Fastest spread; launched DDoS

4 Mydoom 2004 Email Worm
.exe files attacks

Rival to Mydoom/Bagle; created

5 Netsky 2004 Email Worm Attached .pif/.scr files in emails
by German student

Email
Subject lines like “230 dead in Turned PCs into botnets; social
6 Storm Worm 2007 Worm/Botnet
Europe storm” engineering via news headlines
Builder

Conficker Spread mainly via networks, Infected millions globally; huge

7 2008 Worm/Botnet
(partially email) but email phishing possible botnet

2014–
Trojan/Phishin Fake invoice or payment emails Spread malware, ransomware;
8 Emotet 2021,
g Botnet with Word/Excel attachments used macros; returned in 2023
2023
State-
APT28 / Fancy 2015– Fake login emails targeting Hacked NATO, media, US
9 Sponsored
Bear 2020+ high-profile entities elections; Russia-linked group
Phishing

Some phishing emails with fake Affected 200K+ machines;

10 WannaCry 2017 Ransomware
job/invoice attachments demanded Bitcoin ransom

BEC Attacks 2015– Social Spoofed CEO/CFO emails $50+ billion losses (FBI, 2023);
11
(general trend) 2025 Engineering asking fund transfers very common in businesses

RaaS (Ryuk, 2020– Ransomware- Emails with zip, PDF, or Sold ransomware kits via dark
12
LockBit, etc.) 2025 as-a-Service DocuSign malware web; email = main entry point