In order to hit OCA EMAIL OTP API Gateway Endpoint, client must be authenticated. OCA EMAIL API Gateway uses Basic Authentication. Username and password must be encoded with base64 separated by colon and put the encoded credentials into Authorization Header.
Example:
Username: test@gmail.com
Password: test123
Base64Function(test@gmail.com:test123) => dGVzdEBnbWFpbC5jb206dGVzdDEyMw==
Please attach Credentials in Authorization header in your http request like this: