Anatomy of an Email

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What You'll Learn

Every email has a structure that makes it understandable by humans and machines. From the subject line you see in your inbox to the invisible headers that carry technical details, each part plays a role in making sure your message is delivered, displayed, and understood.

📖 Anatomy of an Email

Lesson 3

The Basic Structure of an Email

An email is not just text—it has multiple layers:
  • 1. Headers → Hidden data that tells email servers and clients about the sender, recipient, routing, and technical details.
  • 2. Subject → The short title that appears in your inbox.
  • 3. Body → The main content, either plain text or formatted with HTML.
  • 4. Attachments → Files included with the message.
  • 5. MIME (Multipurpose Internet Mail Extensions) → The standard that allows emails to handle rich content like images, styled text, and attachments.

1. Headers (the invisible backbone)

Headers are like the envelope details on a physical letter. Some important ones:
  • From: Who sent the email.
  • To: Who should receive it.
  • Date: When it was sent.
  • Subject: Title of the email.
  • Message-ID: A unique identifier.
  • Received: Shows the path the email took across servers.
(There are many others, like Reply-To, CC, BCC, Return-Path, but these are the basics.)

2. Subject Line (the first impression)

  • The subject line decides whether your email gets opened.
  • Best practice: Keep it clear, short, and relevant.

3. Body (the message itself)

  • Can be Plain Text (basic, universally supported).
  • Or HTML (allows formatting, colors, links, images).
  • Good practice: Always send both plain text and HTML versions for compatibility.

4. Attachments

  • Any file can be attached (PDF, image, audio, etc.).
  • Attachments are encoded in a special format so they can travel safely across email systems.

5. MIME (Making Emails Smarter)

Before MIME, emails could only send plain text.
With MIME:
  • Attachments are possible.
  • Emails can mix text, images, and styles.
  • Different languages/scripts can be used.
In short, MIME turned emails from “letters” into “multimedia packages.”

🥋 Sensei Tip:

Think of an email like a package delivered by courier:
  • Headers = the label on the box (who it’s from, where it’s going, tracking info).
  • Subject = a sticky note on the box that says “What’s inside.”
  • Body = the actual contents of the package.
  • Attachments = extra gifts tucked inside.
  • MIME = the packaging technology that lets you fit anything inside safely.
Master the anatomy of an email, and you’ll never be confused by what’s under the hood again.
⏱️ Est. reading time: 2 minutes

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