The long awaited Cumulative Update 3 for Exchange Server 2013 was released today by the Exchange Team (KB2892464). This update raises Exchange 2013 version number to 15.0.775.38.

This CU contains the following functional enhancements:

• Usability improvements when adding members to new and existing groups in the Exchange Administration Console
• Online RMS available for use by non-cloud based Exchange deployments
• Improved admin audit log experience
• Windows 8.1 / Internet Explorer 11 no longer requires using OWA Light

The CU contains the following fixes:

• MS13-061 Vulnerabilities in Microsoft Exchange Server Could Allow Remote Code Execution (2876063)
• 2865161 “Errors: Failed exporting item id: from source id” when you try to copy search results in an Exchange Server 2013 environment
• 2871980 Child domains are not displayed for selection when you create a mailbox by using EAC in an Exchange Server 2013 environment
• 2878160 “The Active Directory user wasn’t found” error when you create or update an In-Place eDiscovery search in an Exchange Server 2013 environment
• 2882608 Exchange Server 2013 does not share the inproxy.dll file
• 2886115 Retention policies are not applied to Exchange Server 2013 mailboxes when user accounts are on different domains
• 2888274 WebClientReadFormQueryString string and WebClientEditFormQueryString string return incorrect URLs in an Exchange Server 2013 environment
• 2888315 Event 2112 or 2180 is logged when you try to back up a database in an Exchange Server 2013 environment
• 2888612 Retention policy does not work after you run a cmdlet in an Exchange Server 2013 environment
• 2889786 Sign-in format for Outlook Web App on mobile devices is not adjusted according to the Set-OwaVirtualDerictory cmdlet in an Exchange Server 2013 environment
• 2890650 Items in the Drafts folder are not stamped with the retention policy tag in an Exchange Server 2010 or 2013 environment
• 2895487 “Copy Search Results” option does not work in an Exchange server 2013 environment
• 2895500 DBCS characters appear garbled when you run some PowerShell scripts in EMS in an Exchange Server 2013 environment
• 2895678 “Nombre de usuario\dominio” is displayed unexpectedly on the Spanish version of the OWA and EAC logon pages in an Exchange Server 2013 environment
• 2902929 You cannot forward an external meeting request in an Exchange Server 2013 environment
• 2902929 You cannot forward an external meeting request in an Exchange Server 2013 environment
• 2902933 “Generate incident report” does not display the “Bcc” field in an Exchange Server 2013 environment
• 2902934 Korean language localization issue in Exchange 2013 OWA user interface
• 2902936 You cannot change SMTP addresses for distribution groups by using EAC in an Exchange Server 2013 environment
• 2902938 You cannot preview Office documents in shared folders by using Outlook Web App in an Exchange Server 2013 environment
• 2902939 EMS connection error when you separately install an Exchange Server 2013 Mailbox server and a Client Access server
• 2883203 Exchange Server 2013 restarts frequently after Cumulative Update 2 is installed
• 2890814 No redirection to the Outlook Web App URL for Exchange Online users in an Exchange hybrid deployment

This Cumulative Update includes schema and AD changes, so make sure you run PrepareSchema / PrepareAD. After updating, the schema version will be 15283.

Note that Cumulative Updates can be installed directly, i.e. no need to install RTM prior to Cumulative Updates. Note that once installed, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles. The order of upgrading servers is irrelevant, unlike with previous generations of Exchange.

Finally, and I can’t emphasize this enough: For 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. When you lack such facilities, hold out a week or two and monitor the comments on the release article or TechNet forum for any issues.

You can download Exchange 2013 Cumulative Update 3 here; CU3 UM Language Packs can be found here. More details about these changes, preparing Active Directory or installing this Cumulative Update can be found in the original announcement.