Q: Do I need CDO patch for Exchange 5.5 if I decide to run outlook tool from client
A: Exchange Server 5.5 is no longer a supported product, as described at http://support.microsoft.com/lifecycle/?p1=1776.  Microsoft’s Lifecycle policy can be found at http://support.microsoft.com/lifecycle/?LN=en-us&x=8&y=6.  If you are a Premier Customer you can contact your Technical Account Manager to discuss the Lifecycle Policy.