We encountered this problem during our initial testing. We had configured SSL-Explorer to listen on a non-standard port and started to get 404 errors in OWA. The problem lies with OWA not processing the Host header correctly when the non-standard port is not being listened to by the OWA server.

This was resolved in testing by forcing the OWA server to listen on the non-standard port. If you need OWA to still listen on 443 then go to the advanced options on the "Web site" property page and create an additional web site identity which listens on your non-standard port.

404 errors with OWA 2007 - updated info

A case has been discovered where 404 errors can occur on OWA2007 if IIS is set to accept client certificates on the OWA site.

To resolve this problem, please do the following on the Exchange Server:

• Open up Internet Information Services (IIS) Manager.
• Go to Sites->Default Web Site->OWA
• Click on SSL Settings.
• Change the client certificates radio option from Accept to Ignore and click Apply.