Unable to add .com domain to my mail hosting

Unable to add .com domain to my mail hosting

I am unable to add a .com domain to my email hosting account, it gives me the error "Free domains with extensions such as .tk, .cf, .ml are not supported" 

Last time I checked,  .com domains were not among those which qualify as 'free'.  

I submitted a support request 2 days ago, but have heard nothing in response.