My cwp email does not work with my node app

I configured my cwp email using port 25 with my node app but it shows server cannot be found. When i replaced the email with my cpanel email(shared hosting) it worked perfectly... please help

do you have the domain on CWP but not the user even if you host your mail externally CWP will look in the local map first to resolve any domain hosted on the server , you can change mail routing for the domain to external and remove the dns record from the local dns instance