When an AI edit quietly stops your sign-up emails
A new user signs up, sees "Check your inbox", and waits. The email never arrives. They can't confirm their account, so they leave. You don't hear about it, because from your side the sign-up looked fine.
What happens
Transactional emails (sign-up confirmation, magic links, password resets, receipts) depend on a few small pieces: an email provider API key, a verified sending domain, a "from" address, and the code that calls the provider. An AI edit can break any of them without touching the page you were working on:
- It swaps the email library or "simplifies" the send function, and the new call is never awaited, so it fails after the response is already sent.
- It changes the from address to one on a domain that isn't verified, so the provider rejects every message.
- It moves the send into a try/catch that swallows the error.
- It renames or drops the environment variable holding the API key, so production sends with an empty key.
The form still shows success, so nothing looks wrong.
A quick check after any AI edit near auth or email
- Sign up on the live site with a real address you control (a plus address like you+test1@gmail.com works). Check the inbox and the spam folder.
- Do the same for a password reset or magic link.
- Open your email provider's dashboard and look at recent sends. Rejected, bounced or missing messages show up there before users complain.
- Search your server logs for errors from the email provider around the time you tested.
If something fails, paste the provider's error and your send function into your AI tool and ask: "Make this email send await the result and show a visible error if it fails. Don't change anything else."
Catch it without remembering to
You won't test your inbox after every change. FlowPatrol runs your sign-up, login and checkout against your live app on a schedule and emails you as soon as one breaks, with a ready-to-paste fix prompt. Run a free scan on flowpatrol.app.