Exchange 2013 CU9 (Cumulative Update 9) was released on 6/16/2015 and is a very recent release of Exchange 2013, however the most recent release is CU12 which was released in May 2016.
Warning: CU9 contains an issue that was introduced in CU8 where there is an increased IOPS write load that can cause mail delivery delays to the mailbox database. For this reason I would not install CU9 and would recommend installing at least CU11 which was the release that resolved this issue.
Where to begin:
- For convenience, here is the link to download the latest version of Exchange 2013.
- Instructions to Upgrade an existing Exchange 2013 to CU9.
- Remember on new deployments, you can deploy Exchange 2013 from the CU Rollup itself, saving time (walkthrough links above).
Prominent changes and new features in CU9:
- New signout.aspx code introduced in CU8, but left dormant and unactivated has finally been activated by default in CU9.
What does this code do? Instead of simply sending the end user back to the logon form when they logout OWA (or EAC/ECP), Exchange will send the user to a new static logoff page which recommends that the user close their browser.
Why did they make this change? Microsoft made this change to provide a more consistent logoff experience regardless of the authentication type used (Forms Based, Basic, or Integrated Windows auth). Beyond this, with logon and logoff using different pages, either page could be changed or customized without impacting the other.
What to look out for: Third application integration could potentially be affected by this change, customized logon pages could be impacted as well.