Supabase · api · fg-0198

Supabase Auth confirmation and magic link emails fail with Email address not authorized or hit a rate limit

Email address not authorized when signing up anyone outside the project team

Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100

Cause

Without custom SMTP, Supabase sends only to members of the organization's team and caps sending at 2 messages per hour. After you add custom SMTP the cap starts at 30 per hour until you raise it.

Fix

Configure a custom SMTP provider before launch, then raise the email rate limit on the Auth rate limits page to match expected signups.

Apply

Dashboard: Authentication > Emails > SMTP Settings > Enable custom SMTP
Dashboard: Authentication > Rate Limits > Rate limit for sending emails

Affects: Hosted Supabase projects using the built-in email service (no custom SMTP configured)

Sources

https://supabase.com/docs/guides/auth/auth-smtp

Have your agent know this before it fails

claude mcp add --transport http footgun https://getfootgun.com/api/mcp