Outlook clients couldnt connect to users mailboxes on CAS role. Making use of Exchange 2007 CAS mailboxes do resolve in outlook but users cant open shared calendars and resources With help of Microsoft support we were able to find that the service Microsoft Exchange Address Book uses same port 6004 as outlook anywhere. Now with catch 22 if i change OWA port 6004 the Microsoft Exchange Address Book service starts great but have problems with OWA and RPC. We are still working on it, just hoping somebody has a fix for this already Has anyone came accross this problem and fixed it

Have you hard-coded the ports? I have never heard of this issue.

It is a new install with default settings. We found the port conflict with PortQry. http://www.microsoft.com/downloads/details.aspx?FamilyID=8355e537-1ea6-4569-aabb-f248f4bd91d0&displaylang=en Thank you for the reply. Ok we have found it [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\NTDS\Parameters\NSPI interface protocol sequences] with port bind 6004. You should not delete this if the server is a Global Catalog server!!!!!!!!! In my case it was not. I deleted it and restarted server. Now it is working If it is a BDC adding the global catalog role also worked with out deleting the Regedit.