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.
What email is and what it can carry
The address, the services, and what you can send.
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.
Google's free email service, started in 2004.
Microsoft's free email service.
Yahoo's free email service.
You can open email in a browser (webmail) or in a mail app on a phone or computer.
- 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
- 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 |
|---|---|
| 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 |
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 |
| 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. |
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.
Attachments and good email manners
Size limits, and how to write to customers.
- You attach a 50 MB fileThe file is bigger than the provider's limit.
- limitLimit is checkedGmail allows 25 MB per email when sending; other services set their own limits.
- Cannot be sent as an attachmentShare it as a cloud link instead (Gmail offers a Google Drive link).
- 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
- Use informal or abusive language
- Ignore complaints
- Add unnecessary personal opinions
- Open attachments from unknown senders
The protocols behind email and the web
SMTP sends, POP3 and IMAP receive. Plus HTTP and FTP.
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.
| 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 |
HTTP is named after Hypertext, not Hyperlink. FTP moves Files, not Forms. IMAP starts with Internet, not Immediate.
Client/server, internet services and e-services
Telnet, FTP, Gopher, and e-learning, e-banking, e-commerce.
- ClientA program on your computer asks for something.
- RequestIt travels over the network.
- ServerA program on a remote computer answers.
- Telnet: live login to a distant computer
- Chat rooms, video conferencing
- FTP: fetch files
- Gopher: an early menu-based system for finding documents
- World Wide Web, web services
Learning through technology, any time, anywhere. India's SWAYAM and DIKSHA are examples.
Doing bank work online.
Buying and selling goods and services online.
Electronic messages, the subject of this page.
Quick revision
Full forms, traps and one-line facts.
- 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
- 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.
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.