That wouldn't have anything to do with Apache. I don't know what your network configuration is, obviously but are the working servers using the same firewall/router as the one in question? What router/firewall are you using? Cisco for example, by default, disables SCP. I suspect the problem is not with Postfix but with your firewall/router not allowing Postfix to see the TLS request.
Last edited by gw1500se; 23rd March 2011 at 19:57.