Email: Parts of a Message, Cc and Bcc, SMTP, POP3, IMAP and Internet Services
How email works, the parts of an email, Cc and Bcc, attachment limits, good email manners, the protocols behind it (SMTP, POP3, IMAP, HTTP, FTP, Telnet) and other internet services.
Email (electronic mail) is a way to send messages from one computer or phone to another over the internet. One email can go to one person or many people at once. It can carry text and also attachments such as audio, video, photos and documents. This page covers what Punjab Police SI and Constable papers ask: the parts of an email, Cc and Bcc, attachment limits, good email manners, the protocols SMTP, POP3 and IMAP, and related internet services like HTTP, FTP and Telnet.
1971
First network email
Ray Tomlinson, ARPANET
@
Joins user name and domain
Chosen by Tomlinson
25 MB
Gmail attachment limit
Per email, when sending
3
Main mail protocols
SMTP, POP3, IMAP
What email is and what it can carry
The address, the services, and what you can send.
KEY TERM
Email address
Every email address has two parts joined by the @ ("at") sign. The part before @ is the user name. The part after @ is the domain: the mail service or organisation. Example: in ravi@example.com, "ravi" is the user name and "example.com" is the domain.
ravi→@→example.com
Service
Gmail
Google's free email service, started in 2004.
Service
Outlook.com
Microsoft's free email service.
Service
Yahoo Mail
Yahoo's free email service.
You can open email in a browser (webmail) or in a mail app on a phone or computer.
WHAT ONE EMAIL CAN CARRY
Text in the body
Audio and video files as attachments
Photos, PDFs and other documents
The MIME standard lets non-text files travel by email
WHO IT CAN GO TO
One person
A group of people, using To, Cc and Bcc
A mailing list: one address that forwards the mail to every member
Internet service
What it is
Email
Messages that wait in your mailbox until you read them
Chat room
Live text talk among many people who are online together
Mailing list
One address that sends a message to all subscribers
From the user's side, the internet gives all three: email, chat rooms and mailing lists.
QUICK CHECK
Using mail, what you can send to one person or a group of persons? I. Text II. Audio files III. Video files
Tap an option to answer
Answer: B — I, II and III
Punjab Police SI, 2022. Text goes in the body; audio and video go as attachments. The only real limit is file size, not file type.
QUICK CHECK
From end-user perspective, which of the following services are provided by Internet? I. Email II. Chat rooms III. Mailing list
Tap an option to answer
Answer: C — I, II and III
Punjab Police SI, 2022. All three are standard internet services for users. None of them is left out, so pick "all three".
The parts of an email: From, To, Cc, Bcc
The header fields every paper asks about.
Field
What it shows
From
Email address of the actual sender
To
The main receiver or receivers
Cc (Carbon copy)
Extra receivers; everyone can see these addresses
Bcc (Blind carbon copy)
Extra receivers; their addresses are hidden from the others
Reply-To
Where your reply will go, if different from From
Subject
A short title of the message
CC AND BCC SIDE BY SIDE
Cc
Bcc
Full form
Carbon copy
Blind carbon copy
Others see it?
Yes
No, hidden
Use both together?
Yes
Yes
Cc and Bcc are not mutually exclusive. You can fill both in the same email.
Mailbox folder
What it holds
Inbox
Mail you received.
Drafts
Mail you started but did not send.
Sent
Copies of mail you sent.
Spam
Unwanted bulk or suspicious mail.
Trash
Deleted mail, kept for a short time.
KEY TERM
Modem
A modem (modulator-demodulator) is a device that connects a computer to the internet. It changes the computer's digital signal into a form the phone, cable or fibre line can carry, and back again.
Computer→Modem→Internet
QUICK CHECK
What does the "From" field in an email message header indicate?
Tap an option to answer
Answer: B — Email address of the actual sender
Punjab Police Constable, 2025. From = the sender. To = the receivers. Reply-To is the trap: it decides where replies go.
QUICK CHECK
Which of the following statements is/are FALSE? (i) A modem is a device that connects a computer to the internet. (ii) 'Cc' and 'Bcc' are mutually exclusive when used in emails simultaneously.
Tap an option to answer
Answer: A — Only (ii)
Punjab Police SI, 2023. Statement (i) is true. Statement (ii) is false, because you can fill Cc and Bcc in the same email.
Attachments and good email manners
Size limits, and how to write to customers.
WHAT HAPPENS WITH A BIG ATTACHMENT
You attach a 50 MB file
The file is bigger than the provider's limit.
↓
limit
Limit is checked
Gmail allows 25 MB per email when sending; other services set their own limits.
↓
Cannot be sent as an attachment
Share it as a cloud link instead (Gmail offers a Google Drive link).
The email does not turn into a zip file by itself, and it is not split into separate emails.
DO
Reply promptly to customer questions
Write a clear subject line
Use polite, simple language
Use Bcc when receivers should not see each other's addresses
DON'T
Use informal or abusive language
Ignore complaints
Add unnecessary personal opinions
Open attachments from unknown senders
QUICK CHECK
When you attach a large file (such as 50 MB) to an email and try to send it, what happens?
Tap an option to answer
Answer: C — The email cannot be sent due to attachment size limits set by the provider.
Punjab Police Constable, 2025. Providers cap attachment size (Gmail: 25 MB), so a 50 MB file cannot go as an attachment.
QUICK CHECK
In e-commerce, which of the following is considered a best practice when communicating with customers via email?
Tap an option to answer
Answer: C — Prompt responses to customer inquiries
Punjab Police Constable, 2024. Quick, polite answers build customer trust. The other three choices push customers away.
The protocols behind email and the web
SMTP sends, POP3 and IMAP receive. Plus HTTP and FTP.
KEY TERM
Protocol
A protocol is a set of rules that two computers follow to talk to each other. Email uses one protocol to send mail and another to receive it.
Your app→SMTP → mail server→POP3 / IMAP → receiver
THE THREE MAIL PROTOCOLS
SMTP
POP3
IMAP
Job
Sends mail
Downloads mail
Manages mail on server
Mail stays
—
Usually on one device
On server, synced
Port
25 / 587
110
143 / 993
SMTP = Send. IMAP keeps your phone, laptop and webmail showing the same folders.
Short form
Full form
Used for
SMTP
Simple Mail Transfer Protocol
Sending email
POP3
Post Office Protocol version 3
Downloading email
IMAP
Internet Message Access Protocol (exams also write "Internet Mail Access Protocol")
Reading and managing email on the server
HTTP
Hypertext Transfer Protocol
Web pages in a browser (HTTPS = secure)
FTP
File Transfer Protocol
Copying files between computers (ports 20, 21)
MIME
Multipurpose Internet Mail Extensions
Sending attachments by email
REMEMBER
HTTP is named after Hypertext, not Hyperlink.FTP moves Files, not Forms. IMAP starts with Internet, not Immediate.
QUICK CHECK
IMAP is related to managing and retrieving email from the receiving server. What is the full form of IMAP?
Tap an option to answer
Answer: B — Internet Mail Access Protocol
Punjab Police SI, 2021. IMAP begins with Internet and has Access in it. The official name says Message, but among these options the answer is "Internet Mail Access Protocol".
QUICK CHECK
Web browsers operate using HTTP protocol. What is the full form of HTTP?
Tap an option to answer
Answer: D — Hypertext Transfer Protocol
Punjab Police SI, 2021. HTTP moves hypertext (HTML pages) from a web server to your browser. "Hyperlink" is the trap.
QUICK CHECK
In context to internet, ______ is the full form of FTP.
Tap an option to answer
Answer: B — File Transfer Protocol
Punjab Police SI, 2021. FTP copies whole files between a client and a server. The wrong options swap in "Form" or "Terminal".
Client/server, internet services and e-services
Telnet, FTP, Gopher, and e-learning, e-banking, e-commerce.
THE CLIENT/SERVER MODEL
Client
A program on your computer asks for something.
↓
Request
It travels over the network.
↓
Server
A program on a remote computer answers.
FTP (file client ↔ FTP server) and Telnet (terminal client ↔ Telnet server, port 23) both work on this model.
COMMUNICATION SERVICES
Email
Telnet: live login to a distant computer
Chat rooms, video conferencing
INFORMATION RETRIEVAL SERVICES
FTP: fetch files
Gopher: an early menu-based system for finding documents
World Wide Web, web services
E-service
E-learning
Learning through technology, any time, anywhere. India's SWAYAM and DIKSHA are examples.
E-service
E-banking
Doing bank work online.
E-service
E-commerce
Buying and selling goods and services online.
E-service
E-mail
Electronic messages, the subject of this page.
QUICK CHECK
______ works on a client/server model. I. FTP II. TELNET
Tap an option to answer
Answer: D — Both I and II
Punjab Police SI, 2021. In both, a client program on your machine connects to a server program on a remote machine. Neither is peer-to-peer.
QUICK CHECK
Which of the following is a communication service on the Internet?
Tap an option to answer
Answer: A — Telnet
Punjab Police SI, 2023. Telnet opens a live session with a distant computer, so it is a communication service. FTP, Gopher and web services only fetch information.
QUICK CHECK
________ relates to learning through the use of technology, which enables people to learn at any time or anywhere.
Tap an option to answer
Answer: C — E-learning
Punjab Police SI, 2023. "Learning" plus "any time, anywhere" means e-learning. The others are banking, messaging and online trade.
Quick revision
Full forms, traps and one-line facts.
FLASHCARDS
Full forms: tap to check
Email
Electronic mail
Cc
Carbon copy
Bcc
Blind carbon copy
SMTP
Simple Mail Transfer Protocol
POP3
Post Office Protocol version 3
IMAP
Internet Message (Mail) Access Protocol
HTTP
Hypertext Transfer Protocol
FTP
File Transfer Protocol
MIME
Multipurpose Internet Mail Extensions
Modem
Modulator-demodulator
COMMON TRAPS
From is the sender; Reply-To decides where replies go.
Cc and Bcc can be used together. They are not mutually exclusive.
SMTP sends; POP3 and IMAP receive.
HTTP = Hypertext, not Hyperlink.
Telnet is a communication service; FTP and Gopher are information retrieval.
Also asked onceTap to open
A 50 MB attachment cannot be sent as an attachment because of the provider's size limit (Gmail: 25 MB).
In e-commerce, the best email practice is a prompt response to customer questions.
E-learning = learning through technology, any time and anywhere.
Ray Tomlinson sent the first network email in 1971 and chose the @ sign for addresses.
CHECK YOURSELF
You email a notice to 40 trainees. They should not see each other's addresses, but your officer should openly get a copy. Which fields do you use?
Show answer
Put the officer in Cc so everyone can see the copy went to them. Put the 40 trainees in Bcc so their addresses stay hidden. Using Cc and Bcc together is allowed.
❧
Frequently Asked Questions
What is email in simple words?
Email (electronic mail) is a way to send messages over the internet. One email can go to one or many people and can carry text and attachments like photos, audio and video.
Who sent the first email?
Ray Tomlinson sent the first network email in 1971 on ARPANET. He also chose the @ sign to join the user name and the computer's name.
What is the full form of Cc and Bcc?
Cc means carbon copy and Bcc means blind carbon copy. Everyone can see Cc addresses, but Bcc addresses are hidden from the other receivers.
Can I use Cc and Bcc in the same email?
Yes. Cc and Bcc are not mutually exclusive, so you can fill both fields in one email.
What does the From field in an email show?
The From field shows the email address of the actual sender. The To field shows the receivers, and Reply-To shows where replies will go.
What is the difference between SMTP, POP3 and IMAP?
SMTP sends email. POP3 downloads email, usually to one device. IMAP keeps email on the server and syncs it across all your devices.
What is the full form of IMAP?
The official name is Internet Message Access Protocol. Exam papers often write it as Internet Mail Access Protocol.
What is the maximum attachment size in Gmail?
Gmail lets you send attachments up to 25 MB per email. For bigger files it offers a Google Drive link instead.
What are the full forms of HTTP and FTP?
HTTP is Hypertext Transfer Protocol, used by web browsers. FTP is File Transfer Protocol, used to copy files between computers.
Is Telnet a communication service?
Yes. Telnet gives you a live login session on a distant computer, so it is a communication service. FTP and Gopher are information retrieval services.