Hi Guys,

I have ran into quite an interesting problem - and it seems it appeared out of nowhere.
I have an Exchange 2007 server, where the autodiscover service stopped working. I'll try and post as much details as possible.

My internal and external URLs are different.

Browsing to the Autodiscover service on https://mydomain/autodiscover/autodiscover.xml returns the expected error 600 Invalid request.

In EMS the output for Test-OutlookWebServices is as follows:

However Outlook (editions from 2007 to 2013) are not happy apparently:

Output is as follows:

I use self-signed certificates, that has not changed or expired.
The local DNS has the _autodiscover SRV record set correctly.
Local Firewall is accepting traffic on port 80 and 443 between the CAS server and the local network.

If needed: I get "Operation Failed. An object cannot be found" when I try and download the OAB.

I am out of ideas and any help will be greatly appreciated.

Shaun