← Ship It
0660 min

Talk to humans.

Send an automatic confirmation email when someone signs up — the site reaches the real world.

northside-astronomy.vercel.app
The demo club site confirming a welcome email was sent
Module 06 — automatic welcome emails

The site now reaches into the real world and lands in someone's inbox. It feels like a real company.

The welcome email in an inbox

The automatic welcome email, landing in a real inbox.

Concepts

  • Transactional email = automatic emails triggered by an action (welcome, receipt, reset).
  • Resend is an email API: your backend asks it to send a message.
  • Domain verification: to send "from" your own address, you prove you own the domain. (Instructor handles this once.)
  • This happens in the backend, right after the signup is saved.

Talking points

  • Your site can now email people automatically.
  • The email send happens on the backend, right after we save the signup.
  • Resend needs a verified domain to send as "you" — that's anti-spam, not bureaucracy.
  • Free tier = 100 emails/day, 3,000/month. Way more than a class needs.

Live demo (I do)

  1. Show the (pre-verified, instructor-owned) Resend setup and where the API key goes (.env, same hygiene as Module 4).
  2. Have Claude add an email send to the signup API route: after saving, send a welcome email.
  3. Sign up live with your own address; show the email arrive on the projector.

Student activity (you do)

Students add a confirmation email to their signup flow and write the email's wording for their club. Goal: sign up and receive a real email.

Copy-paste prompts

After a signup is saved in my API route, send a welcome email using
Resend to the address they entered. Put the Resend API key in .env.
The email should welcome them to "[their club]" and say what happens
next. Show me how to test it.

Make the welcome email look nicer with a simple HTML template:
a heading, a short friendly message, and the club name. Keep it
clean and readable on phones.

Where it breaks

  • Emails land in spam / don't send without a verified domain. That's why this is instructor-owned and set up once in advance.
  • Daily limit (100/day). A class of 20 all testing repeatedly can brush it. Stagger testing or use the instructor account thoughtfully.
  • Leaked API key (again). Same .env discipline. Rotate if exposed.
  • Sending to fake/typo addresses. Tie back to Module 5 validation.

Check for understanding

  1. What's a transactional email? Give an example you've received.
  2. Why does Resend require domain verification?
  3. Where in the flow does the email get sent?

Stretch

Also send yourself (the club owner) a notification email for each new signup. Two emails, one event.

For the instructor

Pre-verify your domain and have the Resend key ready before class — domain verification involves DNS records and can take time to propagate; you do not want 20 teens waiting on DNS. Consider providing the key via your run model rather than each student making a Resend account.

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