Microsoft released Cumulative Update 7 (CU7) for Exchange Server 2013 (Ex2013) in early December last year. Exchange Server cumulative updates are a complete release of the product. This means that CU7 can be used to do a new installation, or to update existing instances of Ex2013
CU7 is a recommended update for all current Ex2013 server installations. It includes fixes applied since Ex2013 Service Pack 1 and previous CU releases. It also renders all previous updates to Ex2013 obsolete. CU7 should be used for all updates until Microsoft replaces it with a later release. It should be noted that due to CU7 being the complete Ex2013 installation package, once a server is updated, the update cannot be removed. Removing will uninstall Ex2013 completely. The update also updates the Active Directory schema. For this reason, CU7 should be fully tested in a test environment before deploying to live servers. If live servers are running in a virtualised environment, then it is advisable to take snapshots of the servers before updating. Remember to delete the snapshots once you are happy with CU7 in the live environment. Make sure you have good backups of your Active Directory domain controllers and the schema prior to applying the update.
CU7 is a 1.6GB download and is available here.
There are several key changes and additions contained in CU7. The way that Offline Address Book (OAB) distribution is handled has been changed. In recent releases of Ex2013, OAB creation was tied to a single generation mailbox. In multi-site environments, this meant that requests to download a copy of the OAB resulted in a large download over wide-area network links. CU7 reintroduces the ability to place a shadow copy of the OAB mailbox in different Active Directory sites. This allows the generation of the OAB to be distributed across the network. Requests for OAB download can be fulfilled from local Ex2013 servers in sites near the users, reducing bandwidth usage and improving response times.
It’s a common occurrence to have multi-site deployments of Exchange Server that are comprised of different versions – for example, Ex2013 servers alongside Ex2010 and Ex2007 servers. Prior to Ex2013 SP1, with deployments in mixed current and legacy set-ups, client access to Public Folders on legacy servers was via proxy connections that used RPC/TCP or RPC/HTTP. Ex2013 SP1 introduced the ability for clients to use the MAPI/HTTP protocol to access Public Folder hierarchies. However it also introduced an intermittent issue where some clients could not access the Public Folder hierarchies at all on some legacy servers. Ex2013 CU7 includes a fix for this issue. Now all Public Folder hierarchies can be used from any version of the Outlook client.
The number of nested folders within a Public Folder hierarchy has also been increased with Ex2013 CU7. It now supports up to 250,000 folders in the Public Folder hierarchy.
Backup and restore issues that could sometimes manifest in previous versions of Ex2013 are resolved in CU7. Microsoft recommends that a fresh full backup should be taken after deploying the update.
There are many other fixes and changes in CU7 that you will want to investigate. See this Technet Blog post for an overview and links to the changes and fixes:
It’s certainly an update that you should install (after careful consideration and testing in your test environments). It’s the most feature rich and secure version of Exchange to date. It will provide the best messaging platform for your organisation.