We have a Exchange 2010 environment and use OWA for external access. To secure attachments we use Messageware Attachview which converts attachments to be viewed over the web without the file being downloaded.
Our ISA sever (Microsoft ISA 2000 unfortunately) is configured to only allow SSL traffic for OWA, which all works fine, except for when an attachment is viewed and the request is attempted over http and not https. This causes the ISA server to reject the request as it is not using SSL. if we disable the requirement for SSL then this works, but then owa can be viewed over non secure channels.
I believe the problem is that the ISA server is also offloading the SSL so requests to exchange are coming in over non-secure channels. my thinking is that the attachview link being provided is non-secure as the request is coming in over non secure channels due to the ISA offloading the SSL.
I have configured the external URL for OWA to be the https external url but this is still not working.
Does anyone have any ideas as to why this is the case?