App emails not arriving? The 4 places they get lost
Source checked 19 Oct 2026 · Published 23 Oct 2026 · Last reviewed 23 Oct 2026 · By Ctrl+Z Therapy (how we test)
The short answer
An app's email gets lost in one of four places: never sent, blocked, spam, or a broken link. Supabase's built-in email only delivers to addresses in your project's team, 2 messages per hour, and Resend's testing setup only sends to your own email address until you verify a domain. Google asks all senders to set up SPF or DKIM email authentication for their sending domains, and a Supabase Site URL that still says http://localhost:3000 sends reset links to localhost. Our full guide finds yours on the real Supabase and Resend dashboards, step by step.
What to do
- Never sent: check your logs, and set up custom SMTP in Supabase instead of the built-in email.
- Blocked: on Resend, verify a domain so you can send to addresses other than your own.
- Spam: set up SPF, DKIM and DMARC for your sending domain.
- Broken link: in Supabase, change the Site URL from http://localhost:3000 to your production URL.
Source
- Supabase: Send emails with custom SMTP
- Resend: 403 error (testing emails)
- Google: Email sender guidelines
- Supabase: Redirect URLs
- YouTube: our full 8-minute guide
Checked on 19 Oct 2026. Prices, limits and settings change, so check the source before you rely on them.