On Tuesday December 9, 2014 Microsoft released Exchange Server 2013 Cumulative Update 7 and the UM Language Packs for Cumulative Update 7, 105 days after the release of the previous CU6 update. This release is a little overdue because of a last minute issue that was found moments before the original release date of CU7. As long as it improves the quality of the release this shouldn’t be a problem though.

CU7 contains fixes for issues reported by customers, including the Russian Time Zone issue and fixes for issues identified in MS14-075. Updates for MS14-075 are also available for Exchange Server 2013 Service Pack 1 and Exchange Server 2013 Cumulative Update 6. Because of the Microsoft (N-1) support policy this hotfix won’t be available for CU5.

Two improvements made it into CU7:

• Public Folder Hierarchies now support up to 250,000 folders. More information regarding Public Folders can be found on the On-Premises Legacy Public Folder Coexistence for Exchange 2013 Cumulative Update 7 and Beyond article on the Exchange Team blog.
• OAB Distribution changes as outlined in the OAB Improvements in Exchange 2013 Cumulative Update 7 article on the Exchange Team blog.

Important to note, there are improvements in backing up Exchange Mailbox databases so Microsoft encourages customers to upgrade to CU7 as soon as possible and create a full backup immediately after the upgrade has finished. Under very rare circumstances it is possible that a backup that was created successfully earlier cannot be restored. It is very rare and according to Microsoft no customer has reported this, but you should be aware of this.

Also released at the same time are updates for Exchange 2007 SP3 and Exchange 2010 SP3:

• Exchange Server 2010 SP3 Update Rollup 8 (v2)
• Exchange Server 2007 SP3 Update Rollup 15

Update. Version 2 of the Exchange Server 2010 SP3 Update Rollup 8 was released on December 12, 2014.

Important Hybrid note: customers that are running a hybrid configuration with Exchange 2013 and Exchange Online are required to run on the latest available Cumulative Update to be running a fully supported environment.

As always, you should thoroughly test this Cumulative Update (or the Update Rollup fixes for previous versions) before bringing them to production. There might be undocumented changes in the product that can cause unexpected side effects.

More information regarding Exchange 2013 in general can be found on What’s New in Exchange 2013, Release Notes and Exchange 2013 articles on TechNet.