---
title: "Compare POP3 and IMAP"
subject: "Computer Networks and Security"
chapter: 6
key: "semester_7/computer_networks_and_security:pop3-vs-imap"
source: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/pop3-vs-imap
site: BCT Engineering
---

# Compare POP3 and IMAP

Computer Networks and Security · Chapter 6: Application Layer

- Asked in: 2074 Chaitra, 3 marks
- Video: [POP3 vs IMAP - What's the difference?](https://www.youtube.com/watch?v=SBaARws0hy4) — PowerCert Animated Videos
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/pop3-vs-imap
- Whole chapter: https://www.bctengineer.com/md/semester_7/computer_networks_and_security/chapter-6

## Question

Give a comparison of POP3 and IMAP.

## Short answer

POP3 downloads mail to one client and usually deletes it from the server, while IMAP keeps mail on the server and synchronizes folders across multiple devices. POP3 uses port 110, IMAP uses port 143; IMAP supports server-side search and partial download.

## Answer

Both POP3 and IMAP are mail **retrieval (access) protocols** used by a user agent to fetch messages from the mail server. SMTP only sends mail.

| Point | POP3 | IMAP4 |
|---|---|---|
| Port | 110 (995 secure) | 143 (993 secure) |
| Mail storage | Downloaded to the client; usually deleted from server | Stays on the server |
| Multiple devices | Poor (mail only on one device) | Good (synchronised state on all devices) |
| Folders | Only one inbox on the server | Create and manage folders on the server |
| Partial download | Whole message downloaded | Headers first; parts of a message can be fetched |
| Server-side search | Not supported | Supported |
| Offline use | Good, since mail is local | Needs connection (or cached copy) |
| Complexity | Simple | More complex |
| Server storage | Low | High |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Where is mail stored in POP3 versus IMAP?
   A. POP3 on client (usually deleted from server); IMAP stays on server
   B. Both on client
   C. POP3 on server; IMAP on client
   D. Both deleted
   Answer: A. POP3 downloads; IMAP keeps mail on the server. (Key point: Storage)

2. Which suits multiple devices?
   A. POP3
   B. IMAP
   C. SMTP
   D. Both equally
   Answer: B. IMAP synchronises state across devices. (Key point: Multi-device)

3. Default ports of POP3 and IMAP are:
   A. 110 and 143
   B. 143 and 110
   C. 25 and 110
   D. 80 and 443
   Answer: A. POP3 uses 110, IMAP 143. (Key point: Ports)

## Related in other subjects

- [Browser features; POP, SMTP, IMAP comparison](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Apop-smtp-imap-compare) — Internet and Intranet, chapter 3, asked 2×
- [Compare asphalt, bitumen and tar](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aasphalt-bitumen-tar-comparison) — Civil Engineering Materials, chapter 10, asked 2×
- [Compare DC shunt and series generators](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machine%3Ashunt-series-generator-comparison) — Electrical Machine, chapter 3