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How email works

What actually happens when you click “Send”

First, the plain-English version every team member should understand. The full technical journey — every hop, who controls it, and where it can break — is further down for the curious.

Think of an email like mailing a letter

When you click Send, your computer hands the letter to your post office. Your post office drives it across the country and hands it to their post office. Their post office decides whether to put it in the mailbox — or in the trash.

At every step a different person or company is in charge. So when something goes wrong, the answer to “whose fault is it?” changes depending on where it went wrong.

The one thing to remember

“No bounce-back” does not mean “delivered.”

If your system sent us an email and you didn't get a bounce-back, it usually means the email at least reached our side and we tried to receive it.
But — if your system isn't watching for its own send failures, then “no bounce-back” can also mean the email never actually left your building… and nobody ever told you. That is the silent trap for automated system & alert emails — for example, a monitoring system that emails you when a server goes down, but the alert email itself quietly failed to send.

AFTER YOU HIT SEND, ONE OF THREE THINGS IS TRUE
It worked

You got a reply, or you can see it landed.

Meaning: Delivered. Nothing to worry about.

⚠️
You got a bounce-back

An automatic “delivery failed” email came back to you.

Meaning: It tried and failed — but at least you know, and can fix it.

Silence

No reply. No bounce-back. Nothing.

Meaning: Maybe delivered… or it never sent and your system stayed quiet. The dangerous one.

A bounce-back is actually good news compared to silence — it's proof your system noticed the problem. Silence on a critical alert email is the thing to guard against.

For the curious

Now, the full technical journey

Press play to watch one message travel from a button click to a recipient's inbox — and see who controls its fate at every hop.

You (sender) ISP / network Org / ESP filters Recipient ESP Recipient (mailbox rules)
Ready

Press “Send the email” to begin

Watch one message travel from a button click to a recipient's inbox — and see who controls its fate at every hop.

Whose hands is it in?
Who decides if it's delivered?
How it can go wrong here
L7App/HTTP
L6TLS
L5Session
L4TCP
L3IP
L2Link
L1Physical
delivery log