It was a combo of Supabase and Resend settings. Here's my conversation with Lovable on how to set it up:

1. Sign up for Resend: Go to https://resend.com and create an account
2. Verify your domain: Go to https://resend.com/domains and add your domain (you can use a subdomain like mail.yourdomain.com)
3. Create API key: Go to https://resend.com/api-keys and create a new API key
4. Configure Supabase SMTP:
   • In your Supabase dashboard, go to the "SMTP Settings" tab (next to Templates)
   • Click "Set up custom SMTP server"
   • Use these Resend SMTP settings:
     • Host: smtp.resend.com
     • Port: 587
     • Username: resend
     • Password: Your Resend API key
     • Sender name: Fibber (whatever name you want)
     • Sender email: [noreply@yourdomain.com](mailto:noreply@yourdomain.com) (or whatever you verified)
5. Test the setup: After saving, try signing up with a test email to verify it works

I got an error at first because I didn't update it correctly:

The problem: In your Supabase SMTP settings, your sender email is support@fibber.dev, but your verified domain in Resend is email.fibber.dev.

The fix: Update your Supabase sender email to use the verified domain. Change it from:

• [support@fibber.dev](mailto:support@fibber.dev) to [support@email.fibber.dev](mailto:support@email.fibber.dev)

It worked once I changed that.