On July 9^th Microsoft has released Cumulative Update 2 for Exchange Server 2013 RTM. Besides a large number of (undisclosed) fixes there are several enhancements in CU2:

• Per-server database support – The maximum number of Mailbox databases has been raised from 50 up to 100. The Exchange Server 2013 Server Role Requirements Calculator also has been updated with this information;
• OWA redirection – CU2 introduces a single sign-on experience when using Forms Based Authentication (FBA) which is great in a coexistence scenario;
• High Availability – Exchange 2013 RTM CU2 introduces a new service, the DAG Management Service. The DAG Management service contains non-critical code that used to reside in the Replication service. This change does not introduce any additional complexities in event reporting, either – events are written into the Application event log with the source of MSExchangeRepl and crimson channel;
• Managed Availability -In addition to improvements in various probes and monitors, there have been changes to the responder throttling framework. Prior to Exchange 2013 RTM CU2, many responders were only throttled per-server (e.g., RestartService). Now, these responders are throttled per group ;
• Cmdlet help -Exchange 2013 RTM CU2 introduces the capability for administrators to get updates to Exchange Management Shell cmdlets without needing to deploy a new service pack or cumulative update. Administrators can launch the Exchange Management Shell and run the Update-ExchangeHelp cmdlet to update their local Shell help ;
• OWA Search improvements;
• Malware Filter Rules -Exchange 2013 RTM CU2 introduces the –MalwareFilterRule cmdlets. You can use the –MalwareFilterRule cmdlets to apply custom malware filter policies to specific users, groups, or domains in your organization. Custom policies always take precedence over the default company-wide policy, but you can change the priority (that is, the running order) of your custom policies;

Setup.exe /PrepareSchema /IAcceptExchangeVersionLicenseTerms

The configuration partition in Active Directory has also been changed to reflect changes (additions) in RBAC. To update the configuration partition you can use the following command:

Setup.exe /PrepareAD /IAcceptExchangeVersionLicenseTerms

Please note that with the new Service Model from Microsoft the Cumulative Updates are now a full product with a normal setup application. CU’s will now be released on a quarterly basis. A very important yet dangerous aspect of a full product is that an upgrade will overwrite custom settings on the ‘old’ Exchange Server 2013 server. A common example of this is OWA customization. Also, there’s no roll back model. If you’re not satisfied with the latest CU there’s no way to uninstall and revert to a previous version.

As with all major changes please perform an upgrade first in a test environment and evaluate CU2 appropriately.

These are the Release Notes, the Exchange Product Group announcement can be found here and the download can be found on the Microsoft download site.