I have got Isa 2006 with a rule to publish OWA AND RPC over HTTP to an exchange 2003 configured to back end server and with RPC over HTTP capabilities. Within the domain I can configure rpc over http and owa but from the outside I can’t log in. The authentication for rpc is basic and for owa is form base (Isa 2006 form base) on the exchange 2003 the IIS is configured for basic authentication. The bridge configured HTTPS to HTTPS.
The attachment is a log from ISA 2006 of the failed connection