Firstly, 'port forwarding' is when a firewall or router takes a request on a publicly accessible ip:port and forwards it to an ip.address:port inside your network. I think what you are referring to is 'URL forwarding', a means by which an URL gets resolved to the ip address where the webserver is now.

I use easyDNS.

For hosting httpd on a port other than 80, (port forwarding), one needs to use the more advanced service type, offering URL redirection and/or cloaking, or a combination of global URL forwarding with local PORT forwarding . . .

William