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INTERACTIVE LEARNING TOOL

Protocol Explorer · IMAP

Explore internet protocols with animated messages, real arrival order and packet inspection.

Read the learning guides ↓
PROTOCOL EXPLORERLearn how the internet works
Now learningIMAP · Mailbox synchronizationOverview · 5 steps
Learning progress0%
0 / 14 complete · 0 in progress
Mail Server198.51.100.25InternetRouter192.168.1.1Client192.168.1.10

Protocol overview

IMAP

Active

Internet Message Access Protocol

Work with server-side mailboxes, tagged commands, flags and selective fetches. IMAP supports a mailbox shared across several devices.

Layer
Application (Layer 7)
Default port
143 / 993 implicit TLS
Transport
TCP
Data format
Tagged text commands + mailbox data
Defined in
RFC 9051
Read the complete guide ↗

Packet flow

DNSTCPRequestResponse
No.TimeSourceDestinationProtocolInfoSize
10.000s198.51.100.25192.168.1.10IMAP* OK IMAP ready71 B
20.024s192.168.1.10198.51.100.25IMAPa1 LOGIN learner teaching-only86 B
30.048s198.51.100.25192.168.1.10IMAPa1 OK authenticated75 B
40.072s192.168.1.10198.51.100.25IMAPa2 SELECT INBOX71 B
50.096s198.51.100.25192.168.1.10IMAP* 1 EXISTS105 B
60.120s192.168.1.10198.51.100.25IMAPa3 UID FETCH 42 (BODY.PEEK[HEADER])91 B
70.144s198.51.100.25192.168.1.10IMAP* 1 FETCH (UID 42 BODY[HEADER] {17}126 B
80.168s192.168.1.10198.51.100.25IMAPa4 UID STORE 42 +FLAGS (\Seen)86 B
90.192s198.51.100.25192.168.1.10IMAP* 1 FETCH (FLAGS (\Seen))95 B
100.216s192.168.1.10198.51.100.25IMAPa5 LOGOUT65 B

NAVSPROUT · PROTOCOL FIELD GUIDES

IMAP, packet by packet.

Work with server-side mailboxes, tagged commands, flags and selective fetches. IMAP supports a mailbox shared across several devices.

PROTOCOL FIELD GUIDE

How IMAP works

Work with server-side mailboxes, tagged commands, flags and selective fetches. IMAP supports a mailbox shared across several devices.

Default port
143 / 993 implicit TLS
Transport / carrier
TCP
Category
application

1. Authenticate securely

An IMAP session starts with a server greeting. The lab uses synthetic LOGIN data to expose syntax; real authentication needs TLS.

2. Select a mailbox

SELECT INBOX returns mailbox state including message counts and UIDVALIDITY. Sequence numbers can change when messages are removed.

3. Fetch only what is needed

FETCH can request flags, headers or body sections. UID commands address more stable identifiers within a mailbox validity period.

4. Synchronize flags

STORE changes flags such as \Seen. Untagged responses can report mailbox changes; tagged responses identify command completion.

5. Finish the session

LOGOUT closes the session. Downloaded content and server-side state are separate: fetching a message need not remove it.

Protocol relationships

Protocols cooperate across layers. Compare the neighboring lessons to distinguish addressing, delivery, application semantics and encryption.

Standards and editorial method

Written and implemented independently by NavSprout. Lessons summarize public protocol standards using synthetic documentation addresses and fictional credentials. Consult the standards for complete wire formats and normative behavior.

RFC 9051 ↗

Check your understanding

Which feature is central to IMAP?

Why it’s hereNAVSPROUT ORIGINAL

Reading definitions is easier when you can connect them to a packet. This first-party learning tool pairs static explanations with a visual lab, byte inspection and a short knowledge check. All course data and application resources ship with NavSprout.

  1. Choose DNS and follow the lookup from client to authoritative server.
  2. Switch to the sequence view, then inspect a packet and select a field to highlight its bytes.
  3. Compare TCP with UDP, answer the quiz and export your progress.

Frequently asked questions

What happens when I open a website?

A typical first HTTPS visit can involve DNS resolution, a transport connection, a TLS handshake and an HTTP exchange. Caches, connection reuse and HTTP/3 can change this sequence.

How are TCP and UDP different?

TCP presents a reliable ordered byte stream. UDP preserves individual datagram boundaries without built-in delivery guarantees. Applications choose the behavior they need.

Are these real captured packets?

No. Frames are generated locally for teaching. Header lengths and checksums are calculated, while TLS ciphertext and some negotiation payloads are illustrative. Downloaded PCAP files contain synthetic examples, not live traffic.

Can I learn without JavaScript or an account?

All 14 protocol guides and their lesson explanations are available as ordinary HTML without signing in. JavaScript powers animations, byte inspection, local progress and quizzes.

Where is my progress saved?

Only in this browser’s local storage. Export a progress JSON file to move it to another device. Clearing browser data can remove progress.

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