Resend · api · fg-0408
Resend returns 403 'You can only send testing emails to your own email address'
403 validation_error: You can only send testing emails to your own email address
Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100
Cause
Until a domain is verified, the account can only send to the email address that owns it. The shared resend.dev sender does not lift that restriction.
Fix
Verify a domain and send from an address on it. For automated tests, send to the resend.dev test inboxes instead of real or made-up addresses.
Apply
to: ['delivered+signup@resend.dev'] // also bounced@resend.dev, complained@resend.dev
Affects: Resend API, accounts with no verified domain, as of 2026-10
Sources
- https://resend.com/docs/api-reference/errors
- https://resend.com/docs/dashboard/emails/send-test-emails
Have your agent know this before it fails
claude mcp add --transport http footgun https://getfootgun.com/api/mcp