Exchange 2010 - Publishing Outlook Anywhere using NTLM Authentication on ISA 2006

Microsoft's recommendation is to setup Outlook Anywhere through ISA 2006 using Basic Authentication but I was faced with a dilema trying to get this working in our environment.

After rolling out a new Exchange 2010 Cluster with an F5 load balancer we found if Outlook Anywhere was disabled or setup with basic a user on a domain machine would get prompted for a password. This was random and we have not been able to resolve. This doesn't seem to happen if we don't use the Load Balancer but that is another issue we are working to resolve.

In the meantime we have created a GPO to set the Outlook Exchange Proxy Settings (http://support.microsoft.com/kb/961112 if you are interested). This works well however greys out the options you use to set the client.

So a user that takes their work pc home and tries to connect fails as they are trying to authenticate to OA with NTLM. This can be done!!!!

A frustrated admin had refused to take Microsoft's answer and tested different settings until a suitable solution was found. I followed the settings from the blog and it worked a treat.

http://blogs.pointbridge.com/Blogs/enger_erik/Pages/Post.aspx?_ID=17

Kudos goes to Erik for doing the hard yards. I hope this prevents someone wasting the time I and I am sure Erik has wasted in getting this to work.