Cumulative Update 2 for Exchange Server 2013 was released today by the Exchange Team (KB2859928). This update raises Exchange 2013 version number to 15.0.712.22.

This CU contains the following major changes:

• CU2 increases the maximum number of supported databases per server from 50 to 100 in the Enterprise Edition;
• Enables silent redirection for Outlook Web App (OWA) to Exchange 2007 and Exchange 2013 when using multiple internet-facing AD sites or alternative ExternalURL settings (i.e. for legacy purposes);
• Introduces the DAG Management Service which will offload monitoring and reporting from the Replication Service;
• Shifting several responders from per-server throttling to per-group throttling;
• Support for updating local help files using the cmdlet Update-ExchangeHelp;
• Improvements in OWA Search to indicate search hit locations;
• Introduction of *-MalwareFilterRule Cmdlets to apply custom malware policies to users, groups or domains.

The majority of the enhancements are in line with announcements at TechEd, on which I reported earlier here. Only exception is the Azure File Share Witness which didn’t make it in CU2 but it’s expected to appear in a later build.

Unfortunately, the list of bug fixes in this CU is undisclosed. However, I was able to assemble the following (incomplete) list with things fixed in this CU:

• KB2866064 Can’t load OWA Premium by using Internet Explorer 11 in an Exchange Server 2013, Exchange Server 2010 or Exchange Server 2007 environment
• KB2846288 Information store worker process crashes when you export mailboxes in an Exchange Server 2013 environment
• KB2842504 EAS users incorrectly throttled in an Exchange Server 2013 environment
• KB2830765 “MAPI_E_FAILONEPROVIDER” error when you use a MAPI application in a mixed Exchange Server 2013 and Exchange Server 2007 or Exchange Server 2010 environment
• KB2835562 You can’t disable Outlook Web App access for users in on-premises Exchange Server

This Cumulative Update includes schema and AD changes, so make sure you run PrepareSchema/PrepareAD. Note that Cumulative Updates can be installed directly, i.e. no need to install RTM then CU1 etc. and once installed, you can’t uninstall a CU nor any of the installed roles. The order of upgrading servers is irrelevant, unlike with previous generations of Exchange.

As with any Hotfix, Rollup, Service Pack or Cumulative Update, I’d recommend to thoroughly test this in a test and acceptance environment first, prior to implementing it in production.

You can download Exchange 2013 Cumulative Update 2 here. More details about these changes, preparing Active Directory or installing this Cumulative Update can be found in the original announcement.