GUIDE

Your signup emails aren't arriving

People are signing up and never receiving the confirmation email, or you're seeing "email rate limit exceeded". This catches almost everyone who launches an AI-built app, because the email sender your app started with was never meant for real users.

Why it happens

Auth services like Supabase ship with a built-in email sender for development only. It sends a couple of messages an hour, and in some configurations it only delivers to addresses on your own team. It works perfectly while you test with your own address, then fails silently the moment strangers arrive. Nothing in the builder warns you, because until launch day nothing was wrong.

Fix it before you need it

  1. Connect a real email service. In your auth provider's settings look for SMTP or Custom SMTP, and connect a proper sender (Resend, Postmark, SendGrid and similar all have free tiers). This single change removes the rate limit and the delivery restrictions.
  2. Send from your own domain. Sending as hello@yourdomain.com rather than a shared address is the difference between the inbox and the spam folder.
  3. Add the three verification records. Your email service will give you records to add where you bought your domain. They're called SPF, DKIM and DMARC, and their job is simply proving to Gmail that you're allowed to send as your domain. Paste the values in as given, then wait a few minutes for the service to confirm.
  4. Test as an outsider. Sign up with a personal address you've never used on the app, on a different network, and watch where the email lands. Then repeat with a password reset. Testing with your own team's addresses proves nothing.

If you're in the middle of it right now

My app's signup confirmation emails are not arriving and I may be hitting a rate limit. Tell me: which service currently sends my auth emails, what its sending limits are, and whether it restricts recipients. Then give me the exact steps to switch to a real email provider sending from my own domain, including where each setting lives and what I need to add at my domain registrar. Do not change app code until we have confirmed which sender is being used.

The part people forget

Every email your app sends goes through this same path: confirmations, password resets, receipts, notifications. Fixing the sender once fixes all of them, and it's worth doing before launch rather than during it, because the failure is invisible from your side. Your users don't complain about a missing email; they just leave.

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