Hey there,
Unfortunately, with Sitejet it is not possible to not have a www.your-domain.com … Ultimately, this was an architectural decision. You have to or should commit to one domain, so that you don’t have any
duplicate content under two different domains (your-domain.com and www.your-domain.com) in the net. We decided to use www because it is more common.
Sitejet hosting does not work without a subdomain at the moment.
A redirect unfortunately does not help you at all, because the website is not hosted under your-domain.com, but only under a subdomain.domain.com, respectively www.my-domain
The only workaround possible at the moment would be to export the website and host it somewhere, where the hoster offers that possibility.
Let me know if that helps. 