"POST requests from foreign hosts are not allowed."

[Rancher]

or Does it? I may have loopholed it or whatever, but:
Yesterday I didn't add in the real forums subdomain as $http_host, making it only being the domain I added; and all my members couldn't post.
Here's what I did: My main site is v3.hmotaku.net; and the forums are located at forums.hmotaku.net.
I just declared v3.hmotaku.net as $http_host; ($http_host = 'v3.hmotaku.net' and in result all requests from forums.hmotaku.net (the real forums domain) was blocked by "POST requests from foreign hosts are not allowed." What happened was that all requests were blocked; EXCEPT from v3.hmotaku.net; which was declared at $http_host. So I declared forums.hmotaku.net $http_host as well, and all was fine again. -_-;;

I'm not sure how the whole referer checking thing works in vB; but how exactly did I loophole it? And NO, any other site can't submit; as proved above. =__=;