KACE Product Support

We are an Office365 shop and are having issues with our SMTP setup. We use a relay but the mail is getting blocked. The problem is the system sends as root@kbox2100.domain.com...so it's adding that subdomain that cannot be accepted. There are no options to change the sending address or authenticate with another account. I'm looking for other Office365 customers out there. How are you set up and working?