akhil_styles add a console.log statement inside server/index.js file at line number 32 here, inside the catch block like this:

} catch (error) {
  console.log('error', error);
  res.status(500).send({
    success: false,
    message: 'Something went wrong. Try again later'
  });
}

and add the console.log at line 44 here.

So now when you send an email, you will be able to know the exact reason for the error. check the error message in the terminal log where you have started the Node.js server