How to fix email_address_not_authorized: Email sending to this address is not authorized in Supabase

The most reliable solution is to set up a custom SMTP server:

1. Go to your Supabase dashboard
2. Select your project and navigate to Project Settings → Auth → SMTP Settings
3. Toggle Enable Custom SMTP
4. Configure your SMTP credentials (host, port, username, password)
5. Set the sender email and sender name
6. Click Save

Recommended SMTP providers: Resend, Mailgun, SendGrid, Mailtrap, or AWS SES. Each offers free tiers to get started.

If you need to use Supabase's default SMTP temporarily, add the recipient email as a team member:

1. Go to Organization Settings → Team
2. Click Invite member
3. Enter the email address you want to send to
4. Send the invitation
5. Once accepted, that email will be authorized for receiving Auth emails

Note: This is only a temporary workaround. The default provider has a 2-4 messages per hour rate limit and is not suitable for production applications.

After setting up custom SMTP, improve email deliverability:

1. Access your domain's DNS settings (GoDaddy, Namecheap, AWS Route 53, etc.)
2. Add SPF record (usually looks like: v=spf1 include:provider.com ~all)
3. Add DKIM record (provided by your SMTP provider)
4. Add DMARC record (template: v=DMARC1; p=quarantine; rua=mailto:[email protected])
5. Wait for DNS propagation (can take up to 48 hours)
6. Verify in your SMTP provider's dashboard that records are correctly configured

This ensures emails from your domain don't land in spam folders.

Once custom SMTP is configured, test it:

const { error } = await supabase.auth.signUp({
  email: '[email protected]',
  password: 'TestPassword123!',
});

if (error) {
  console.error('Sign up error:', error.message);
} else {
  console.log('Sign up successful - check email for confirmation');
}

Check your inbox (and spam folder) to confirm the email was received. If still failing, verify SMTP credentials are correct in Supabase settings.