Unfortunately, we don’t manually manage host headers as this doesn’t scale across our client base and infrastructure. Instead they are done automatically based on the URL/Internal Domain that you choose underneath a Reward Gateway top level domain (rewardgateway.com/ .co.uk/ .com.au/ .ie/ .co.nz).
If you point a DNS record directly at our inbound IP addresses, you will see SSL certificate errors and the website will not load. The only supported options are the ones listed in the article named Integrations - Enabling Web Access - Custom Domains under 'Custom Domains'.