Can’t view Outlook owa 2003 externally

Hi Guys I am a newbie so please help, I have installed a dell powerEdge sc1435 with sbs 2003 with the intention of getting exchange working for external use. Currently exchange is working fine internally sending and recieving mail, I am using the pop connector to recieve our mail at the moment from our web hosting company. I am not going to direct mx records at the moment so was just going to use servers ip address. We have a draytek 2600 router which I have port forwarded 444, 443, 4125, 25 to the server, I am trying to view this externally like this https://serverip/exchange/logon.asp but all I get is page cannot be displayed

any help would be greatly appreciated

Kraig