Outlook 2007 fails to connect to Outlook Anywhere via NTLM on Vista

So, firstly an apology for the lack of posts recently... I always said that if I didn't have anything interesting or useful to post I just wouldn't post, so that's what happened…

Anyway, I have been working with a customer to deploy Outlook Anywhere, we used Greg Taylors awesome white paper on this to get UAG to do the necessary publishing and authentication. This worked fine in my test lab but when we configured in production the clients couldn't connect and received perpetual credential prompts...

We did the usual host of troubleshooting (there is plenty of hocus-pocus on internet forums about OA password prompts!) but basically drew a blank… then someone in the project team noticed that their test Windows 7 machine could connect, but the production Vista machines were failing.

After some head scratching and searching we came across the following KB article…


"Consider the following scenario. You have a computer that is running Windows Vista or Windows Server 2008. You configure the computer to use the RPC over HTTP feature to access certain services. In this scenario, the RPC over HTTP module (Rpchttp.dll) may not work correctly. Therefore, the RPC over HTTP connection does not establish successfully. For example, you cannot sign in to Outlook Anywhere or in to Office Communicator. Additionally, you are prompted to provide your user credentials."

So.. We dutifully downloaded and installed this hotfix which resolved the issue J

I wanted to post this here since we don't get to see Vista very often and I was totally unaware of this issue.

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