It’s common for people to hit CORS (Cross-Origin Resource Sharing) issues when using the Resend API. This error typically shows as:
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Access to XMLHttpRequest at 'https://api.resend.com/emails'from origin 'http://localhost:3000' has been blocked by CORS policy:Response to preflight request doesn't pass access control check:No 'Access-Control-Allow-Origin' header is present on the requested resource.
Usually CORS errors happens when you’re sending emails from the client-side.We recommend you to send the emails on the server-side to not expose your API keys and avoid CORS issues.