SMTP for Dummies: Email Explained Like You're Five
Beginner

SMTP for Dummies: Email Explained Like You're Five

Sarah Kim

Sarah Kim

December 31, 2025

6 min read

A beginner-friendly guide to understanding how email works, using simple analogies and zero technical jargon.

What is Email, Really?

Think of email like sending a letter through the postal service, but instead of days, it takes seconds!

The Postal Analogy

šŸ“§ EMAIL                          šŸ“¬ POSTAL MAIL
─────────────────────────────────────────────────────
Your email app         =          Your mailbox
Email address          =          Home address
SMTP server            =          Post office
Internet               =          Mail trucks & planes
Recipient's server     =          Destination post office
Inbox                  =          Recipient's mailbox

How Email Actually Travels

When you hit "Send," here's what happens:

Step-by-Step Journey

    YOU                                           FRIEND
     šŸ“±                                             šŸ“±
      │                                              ā–²
      │ 1. Write email                               │
      │    "Hey, how are you?"                       │
      ā–¼                                              │
ā”Œā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”                                   ā”Œā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”
│  YOUR    │                                   │ FRIEND'S │
│  POST    │ ═══════════════════════════════> │  POST    │
│  OFFICE  │      3. Travels through          │  OFFICE  │
│ (Gmail)  │         the internet             │ (Yahoo)  │
ā””ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”˜                                   ā””ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”˜
      ā–²                                              │
      │ 2. Sorted &                                  │ 4. Delivered
      │    stamped                                   │    to inbox
      │                                              ā–¼
    ━━━━━                                         ━━━━━

What is SMTP?

SMTP stands for Simple Mail Transfer Protocol. It's just the "language" that email servers use to talk to each other.

Think of it Like This:

ā”Œā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”
│                                                         │
│   SMTP is like the RULES for sending mail:              │
│                                                         │
│   šŸ“ Rule 1: Say hello first                            │
│   šŸ“ Rule 2: Tell who you are                           │
│   šŸ“ Rule 3: Say who gets the letter                    │
│   šŸ“ Rule 4: Hand over the letter                       │
│   šŸ“ Rule 5: Say goodbye                                │
│                                                         │
│   If everyone follows the same rules,                   │
│   mail gets delivered correctly!                        │
│                                                         │
ā””ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”˜

A Simple SMTP Conversation

Here's how two mail servers chat (in human terms):

ā”Œā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”
│                                                         │
│   YOUR SERVER:  "Hi! I'm mail.google.com"              │
│                                                         │
│   THEIR SERVER: "Hello! Nice to meet you"              │
│                                                         │
│   YOUR SERVER:  "I have a letter FROM john@gmail.com"  │
│                                                         │
│   THEIR SERVER: "OK, I know john"                      │
│                                                         │
│   YOUR SERVER:  "It's going TO mary@yahoo.com"         │
│                                                         │
│   THEIR SERVER: "OK, mary lives here"                  │
│                                                         │
│   YOUR SERVER:  "Here's the message: Hello Mary!"      │
│                                                         │
│   THEIR SERVER: "Got it! I'll put it in her mailbox"   │
│                                                         │
│   YOUR SERVER:  "Thanks, bye!"                         │
│                                                         │
│   THEIR SERVER: "Bye!"                                 │
│                                                         │
ā””ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”˜

Why Emails Sometimes Fail

āŒ COMMON PROBLEMS
─────────────────────────────────────────────────────────
Wrong address         →  Like writing wrong home address
Mailbox full          →  Recipient's mailbox overflowing
Server down           →  Post office is closed
Spam filter           →  Letter looks suspicious
Blocked sender        →  You're on their "do not deliver" list

Email Addresses Explained

           john.doe@gmail.com
           ─────────┬────────
                    │
    ā”Œā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”¼ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”
    │               │               │
    ā–¼               ā–¼               ā–¼
  john.doe         @            gmail.com
    │               │               │
 Your name    "lives at"    Your post office
 (username)    symbol       (mail provider)

Types of Email Servers

ā”Œā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”
│                                                         │
│   šŸ“¤ OUTGOING (SMTP)                                    │
│   Like dropping a letter in the mailbox                 │
│   Port: 587 or 465                                      │
│                                                         │
ā”œā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”¤
│                                                         │
│   šŸ“„ INCOMING (IMAP/POP3)                               │
│   Like checking your mailbox for new letters            │
│   Port: 993 (IMAP) or 995 (POP3)                        │
│                                                         │
ā””ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”€ā”˜

Key Takeaways

1**Email is like postal mail** - just much faster
2**SMTP is the language** servers use to send mail
3**Your email provider** is like your post office
4**Email addresses** tell servers where to deliver
5**It all happens in seconds** instead of days

Conclusion

That's it! Email isn't magic - it's just computers following simple rules to pass messages around. Now you know more about email than most people!