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Resend

Add an API key, set the from-address in config.ts, and the welcome email already sends after checkout.

Launch Kit sends mail through sendEmail() in libs/resend.ts. Today that helper is used once: the Stripe webhook sends a welcome message after checkout.session.completed.

Key

Create an account at resend.com. Copy an API key into RESEND_API_KEY.

Credential	Env var	What the kit does with it
API key	`RESEND_API_KEY`	Authenticates `resend.emails.send`

No other Resend setting is required in env.

From-addresses

These live in config.ts, not env:

Key	Used?	What to put
`resend.fromAdmin`	Yes	`Your App <hello@your-domain.com>` — this is the `from` on every `sendEmail()` call
`resend.fromNoReply`	No	Reserved. The helper does not read it
`resend.supportEmail`	Footer + legal	A real inbox, or leave empty

Resend’s test sender works without DNS. You can leave the default from-address while you develop. Mail goes to your own account’s inbox.

Verify the domain in Resend, add the DNS records, then set fromAdmin to an address on that domain. Unverified domains will bounce in production.

Send another email

Keep libs/resend.ts. Call it from a server file:

import { sendEmail } from "@/libs/resend";

await sendEmail({
  to: user.email,
  subject: "Your subject",
  text: "Plain text body",
  html: "<p>HTML body</p>",
});

Optional replyTo is already on the helper.