Guide: resolving Supabase Email Rate Limits

The "Identity service error" or rate limit issues encountered during testing are due to Supabase's default email provider, which is strictly limited (typically ~3 emails per hour on free/development tiers).

To support UAT Users and Beta Testers, you must configure a Custom SMTP Provider.

Recommended Steps

1. Choose an SMTP Provider

Sign up for a transactional email service. Popular options include: - Resend (Recommended for simplicity) - SendGrid - Postmark - AWS SES

2. Configure Supabase Dashboard

Once you have your SMTP credentials, follow these steps: 1. Go to your Supabase Project Dashboard. 2. Navigate to Authentication > Settings. 3. Scroll to the Smtp Settings section. 4. Enable Enable Custom SMTP. 5. Enter your provider's details: - Sender email: Your verified sending email. - Sender name: e.g., "MERP25" - Host: e.g., smtp.resend.com - Port: Usually 587 or 465. - User: Your provider's API key or username. - Pass: Your provider's password/secret key. 6. Click Save.

3. Adjust Rate Limits

After enabling custom SMTP, you can increase your rate limits: 1. In the same Authentication > Settings page, find the Rate Limits section. 2. Increase the Max Email Sending Rate (e.g., from 3/hour to 100/hour or more depending on your SMTP provider's tier).

Benefits

• Higher Deliverability: Emails are less likely to land in spam.
• Improved Logging: Track exactly which emails were delivered from your SMTP provider's dashboard.
• Custom Domains: Send from @yourdomain.com instead of a generic Supabase address.

[!IMPORTANT] Ensure you verify your domain with the SMTP provider (via DNS records like SPF/DKIM) to ensure maximum deliverability for your beta testers.