Flutter Web - Send mail directly from the web app

I Am creating a website with Flutter. I need to create a page where you can send e-mail to my personal mail

I tried to use SendGrid but Chrome gives me the following CORS policy error

Access to XMLHttpRequest at 'https://api.sendgrid.com/v3/mail/send' from origin 'http://localhost:55901' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: The 'Access-Control-Allow-Origin' header has a value 'https://sendgrid.api-docs.io' that is not equal to the supplied origin. browser_client.dart:74 POST https://api.sendgrid.com/v3/mail/send net::ERR_FAILED

Anyone with any ideas on how to fix it (not temporarily)?

There is a better way to send mail irectly from Flutter Web