On our old server, the provider installed Smartermail Free edition and we used it to send mail from the mail server when someone filled out contact forms, placed orders etc.. We didn't need to manage a list of email users. However, we had to move to a new server running Windows Server 2019 and they no longer provide email setup services on the server.

Now when we try to send mail via say PHPMailer, and look at the output, we get the error

What settings do we need to change to allow Smartermail to send mail from the web server to outside email addresses?