For a brief period of time on 9/9 (Tuesday), a pre-release version of Update Rollup 4 for Exchange Server 2007 Service Pack 1 (KB952580) was inadvertently made available to Microsoft Update, the Microsoft Update Catalog, and WSUS servers for download. While we quickly identified and removed the update from Microsoft Update within a short period of time, some servers using these distribution methods might have detected, downloaded and/or installed this version of the update.

An issue exists with this pre-release version of the Rollup 4 with regard to the Exchange Web Service (EWS) that creates the potential for a continuous crashing cycle. The final version of this update will be released shortly and we recommend customers who have not already installed the update to wait to do so. For those who have already installed the update, we recommend uninstalling this version. Once a new the final version is made available, all Exchange 2007 SP1 Installations with pre-release version of Rollup 4 installed will be offered the final version which will install over the pre-release.

We apologize for any inconvenience and are working to make sure this does not happen again. While at this time we are not aware of many customers being affected by this, we wanted to let you know in case you are currently testing what you downloaded 2 days ago.