This is a very odd situation so bear with me when explaining this. I have several users scattered out in different remote offices that are haveing authentication issues in outlook 2007 when trying to connect to our exchange 2010 public folder servers (CAS). When the users open outlook it constantly sits at trying to connect and eventually locks the machine up until you use the task manager to close outlook. I have only determined this is a public folder issue because if you hold down the cntrl key and right click on the outlook icon in the taskbar (next to clock) you get and option to see connection status. This shows the server name (one of the CAS) and the type as public folder and the connection status is empty. We opened a microsoft ticket on this and they said it was a client side issue because we have 1700 users connection to the same set of servers with out issues. Well we have reimaged the users desktop, replaced all cableing from the user to the switch, and confirmed the IOS on the routers matches other offices that are working. Still the same problem. Heres the kicker! This problem does not effect other users in the same office and if this paticular user logs into another machine the same problem happens. But if she accesses her mailbox from Web Access she has no problems and if I log this user on here at our home office on the same LAN as the Exchange system she has no issues. But wait theres more. We have deleted the user's mailbox and LAN account. Created a new mailbox and LAN account with a similar name not the same one and when I log on to her machine exacte same issue. I have removed all antivirus software from the machine and still have the same problem. Not until we ran wireshark on her machine did I start seeing some ntlm authentication issues to the exchange system. We manually changed outlook from Negotiate Authentication to Password Authenticatoin (NTLM) and viola her email started syncing??? When i change this setting on the other users they connect also. But why are we not haveing to change this on the other 1700 users? Can anyone please offer some insite in to what the hell is causing this and why it seem to follow the user around. I have been troubleshooting this for weeks and am so frustrated because it just doesnt make any sense. Thankyou to anyone willing to provide any ideas into what could be causing this. When we opened a Microsoft ticket they were convinced that its client side but I have replaced everything.

Hi, Do you use outlook anywhere? Or use outlook via VPN? What is the verison of your Exchang Server? Recommendation: Enabling Kerberos Authentication for MAPI Clients http://blogs.technet.com/b/exchange/archive/2011/04/15/recommendation-enabling-kerberos-authentication-for-mapi-clients.aspx You are repeatedly prompted to enter your credentials when you try to connect to an Exchange mailbox by using Outlook 2007 http://support.microsoft.com/kb/927612 Xiu

Xiu, I looked in the exchange management console and outlook anywhere is setup but to my knowledge it is not being used. The remote sites are connecting to us via IPSEC tunnel over a broadband connection. Our 2010 exchange environment is up to date at sp1 rollup 5. I have looked over some of the docs you referenced and there are some very similar situations in them. I will keep reading and verifying that everything checks out. Thanks for your help