I have just implemented a watchguard firebox 550e on my network. I can access the OWA (exchange 2003) without an issue from within the network. When I access it from outside, I login and a folder list appears on the left, but every view on the right says "there are no items to show in this view" (this applies to all views - mail, contact, journal, etc).
I have incoming HTTP and HTTPS proxies set to forward requests on the MX record to the Exchange server. Email is flowing in and out without an issue, there are just no individual items listed on OWA from the outside.
Everything that I have located on the internet states that setting up HTTP and HTTPS proxies are all that should be needed for OWA which resides on the Exchange server (which is how I am set up).
Any suggestions would be would be appreciated.