I was setting up my home lab and added a Windows XP machine with Outlook 2003 SP3 into the mix. The Exchange server was running 2010 SP1. When trying to setup the Outlook profile, I got the error below.
“Your Exchange Server administrator has blocked the version of Outlook that you are using. Contact your administrator for assistance”.
As I had scripting agent running in my lab while I was writing this article, I quickly checked to see whether the mailbox was blocked from using earlier versions of Outlook. But, it wasn’t.
I was able to setup a profile while using Outlook 2010. That made things clear. I quickly checked to see whether I had a public folder database in my environment and I didn’t. I rarely run Outlook 2003 and hence had opted not to have public folders while installing Exchange 2010.
I created a public folder database named PF1.
Now I could setup my Outlook 2003 profile without any issues.
It would have been nice to have a useful error message 
I see this error only when using a PRF file to update the Outlook 2003 profile (simply changig the name of the server). I can create a profile manually connecting to the same server with the same settings. The Exchange server in question does, in fact, have a public folder store.
Any ideas?
Well ,Nice article.
It resolved my issue for integration of outlook 2003 profile with exchange 2010. i was aware of RPC encryption and manually handled it by checking the “Encryption data ” settings in outlook but was still getting issue because Public folder was not available in exchange2010 . This article helped me a lot.