It worked every time you tried it. Then real people sign up, wait for the confirmation email, and nothing comes. Supabase's built-in sender only delivers to addresses on your project's team, sends 2 messages an hour, and is not meant for production. Your own address is on the team. A stranger's is not.

Sign-up only finishes when the person clicks the link or enters the code in that email. Whatever sends your app's emails decides who gets them, how many go out per hour and whether they land in the inbox. The default senders are made for trying things out, not for strangers arriving from an ad or a post.

Here are the seven causes, and the fix for each.

1. Supabase's default sender only delivers to your team

Unless you set up your own SMTP server, Supabase only sends to addresses that are part of the project's team.…