App Connect

Hi, I tried to configure the Microsoft Exchange Email node in one of the test flows in ACE designer.

When I tried to test it, I am getting below error

{
  "message": "Some fields provided for the Send email action on the Microsoft Exchange Emails object are either invalid or missing.",
  "action": "Ensure that you've provided values for all the mandatory fields and that the values specified for all fields are valid.",
  "detail": "Microsoft Exchange cannot process the request because it is malformed or incorrect.",
  "url": "",
  "data": {
    "errorDetail": "{\"status\":400,\"body\":\"Response code 400 (Bad Request)\"}"
  }
}

The settings are as below.

Any idea what I am missing here ?

thanks