In a 2007 CCR RTMenvironment, can the SP1 upgrade be performed on the CAS/HUB servers well in advance of the mailbox servers themselves being upgraded to SP1, or do they all need to be upgraded at around the same time? Thanks!

Hi Matt, I wouldn't recommend you to install well in advance, upgrade at around the same time and keep the lavel same but read recommendation from Microsoft on it... "We recommend that you upgrade your servers that are running the Mailbox server role after you upgrade your servers that are running the Client Access, Unified Messaging, Hub Transport, or Edge Transport server roles. If you upgrade your servers in this order, you may avoid potential service interruptions. (Upgrading roles in that order will assure that the servers that "front" the functionality for mailboxes are able to communicate with the mailbox server without interruptions, rather than running into problems when trying to communicate with a more-featured back-end server.) We also recommend that you upgrade your Client Access servers that reside in Internet-facing sites before you upgrade your Client Access servers that reside in sites that are not accessible from the Internet. If you are running the Edge Transport server role in your Exchange organization and have created an Edge Subscription, all transport servers that participate in the EdgeSync process must be running the same version of Exchange 2007. You must upgrade all the subscribed Edge Transport servers and all the Hub Transport servers in the Active Directory site to which the Edge Transport servers are subscribed; and you must do so within 15 days of the first upgrade to Exchange 2007 SP1 of any transport server that participates in the Edge Subscription process." http://technet.microsoft.com/en-us/magazine/cc462807.aspx