---
title: "e-mail"
space: "Teacher's Handbook"
url: "https://portal.cs17.org/teachers-handbook/q2/e-mail"
updated: "2026-10-03"
---

### Email Etiquettes

- Shivam covered email etiquettes, which was a very good idea
- After some basics like CC, BCC, he made them write emails for practical things like postponing a standup (😂) etc.



### Emails: How do they work?

Lecture by: Hussain, Duration: 2.5hrs

> Depends on the internet lecture, quick recap if needed.

By the end, they should be able to understand:

- [shanti@cs17.org](mailto:shanti@cs17.org) => shanti (**mailbox**), cs17.org (**domain**)
- Sender mail server first does MX (mail exchange) record query to DNS, gets back hostname (e.g. bwh.frappemail.com in our case)
- Then hostname is used to get IP Address (again DNS call, A/AAAA), e.g. 192.12.45.65
- Sender sends to the IP (using SMTP)
- Receiver mail server uses the "shanti" part to put the message in the right mailbox.



Base material:

![CS17_Email_Essentials_Updated.pdf](/files/CS17_Email_Essentials_Updated.pdf)



Practical Demo:

![](/files/CleanShot 2026-09-15 at 18.42.47@2x.webp)

Useful diagram to explain mailboxes:

```plaintext
Mail Server
│
├── mailbox: ali@cs17.org
├── mailbox: sara@cs17.org
├── mailbox: hussain@cs17.org
└── mailbox: teacher@cs17.org
```



![](/files/CleanShot 2026-09-15 at 18.47.57@2x.webp)



![](/files/CleanShot 2026-09-15 at 18.48.17@2x.webp)

Some notes:

- base64 to binary conversion happens on either side (they know this by now): this is what the MIME standard allows, embedding non-text content in emails.



Full forms: 

- MIME: **Multipurpose Internet Mail Extensions**
  - This was explained by first showing the original / MIME message (an email containing two PDF attachments)
- SMTP: **Simple Mail Transfer Protocol**
- POP3: **Post Office Protocol Version 3**
- IMAP: **Internet Message Access Protocol**



### Ports



Explain when the same server has web server and email server, hence same IP address. But door analogy on how different protocols wait on different doors.



**Not** covered yet:

- Network layers, TCP etc. and security records like DMARC, etc.