# Resend

Resend sends your apps' email (sign-in codes and notices) and receives replies to your support address. Needed only if your app sends email.

**Time:** about 10 minutes, plus waiting for DNS. **Needs:** a domain you own (for example `acme.com`) and access to its DNS.

**No domain?** Skip this page. App email stays off: apps have no address of their own, support and privacy contacts are your own email, and sign-in codes come from Supabase's built-in sender. That sender only delivers to members of your Supabase organization, a few emails an hour, which is fine for trying an app yourself. For outside testers who sign in by email, add a domain and set up Resend.

## Steps

1. Sign up at <https://resend.com>.
2. Open <https://resend.com/domains> → **Add domain**. Use a subdomain such as `apps.acme.com` and turn on **Receiving**. A subdomain keeps your own mail on `acme.com` untouched.
3. Add the DNS records Resend shows to your DNS (in Cloudflare if that is where your domain lives, or use Resend's Cloudflare auto-configure). Wait for the status to become **Verified**.
4. Open **API Keys → Create API Key**. Name it `starwisp`. Permission: **Full access** (it reads domains and creates each app's inbound webhook).
5. Copy the key. It starts with `re_`.

**Least privilege:** Full access is what the factory needs today. Use an account dedicated to Starwisp and send only to people who opted in.

## Where it goes

Console → **Settings → Vault** → card **Resend**:

| Field | Value |
|---|---|
| **API key** | the key (secret `AUTH_SMTP_RESEND_API_KEY`) |
| **Sending domain** | your domain, for example `acme.com` (`AUTH_SMTP_FROM_DOMAIN`) |

Also set **Settings → Identity → App email domain** (for example `apps.acme.com`). Click **Test now**.

**You should now see** a passing test on the card.

## What it gates

Email in your apps (backend and launch stages), including sign-in codes by email.

## What it costs

Estimates from Resend's public pricing: Free is $0 for 3,000 emails a month and 100 a day, with 3 domains. Pro is $20 a month. The 100-a-day limit is reached early if many people request sign-in codes.

## Slow prerequisites

**Domain verification:** minutes to hours, sometimes longer (the time is not published; this is unverified). It must finish before email works. You can do other setup while you wait.

## Rules to know

Resend requires opt-in recipients and watches complaint and bounce rates. Do not send marketing email to people who did not ask.