On June 27, 2017 Microsoft has released its quarterly updates for Exchange 2013 and Exchange 2016. The current version is now at Exchange 2013 CU17 (15.0.1320.4) and Exchange 2016 CU6(15.1.1034.26) . But this time there are some interesting things I’d like to point out.

A couple of days before the release of Exchange 2016 CU6 (15.1.1034.26)
Microsoft blogged about Sent Items Behavior Control and Original Folder Item Recovery. With the Sent Items Behavior Control, a message that’s sent using the Send As or Send on behalf of permission is not only stored in the mailbox of the user that actually sent the message, but a copy is also stored in the delegator mailbox sent items. This was already possible for shared mailboxes, but now it’s also possible for regular mailboxes (like manager/assistant scenarios).

The Original Folder Item Recovery feature is I guess on of the most requested features. In the past (before Exchange 2010) when items were restored after they were deleted, they were restored to their original location. With the Dumpster 2.0 that was introduced with Exchange 2010 this was no longer possible, and items were restored to the deleted items folder. In this case the items had to be moved manually to their original location. With the introduction of the Original Folder Item Recovery the restore of deleted items again takes place in the original folder.

Unfortunately, both Sent Items Behavior Control and Original Folder Item Recovery are only available in Exchange 2016 CU6 (and NOT in Exchange 2013 CU17).

When it comes to security TLS 1.2 is a hot topic. Microsoft is aware of this and working hard towards an Exchange environment that only uses TLS 1.2 (so that TLS 1.1 and TLS 1.0 can be disabled). We are not yet at that stage. Exchange 2016 CU6 does have improved support for TLS 1.2, but Microsoft is not encouraging customers to move to a TLS 1.2 environment only.

.NET Framework and Exchange server continues to be a difficult scenario. This is understandable, Exchange is just a consumer of Windows and .NET so the Exchange Product Group does not have much influence on the .NET (and Windows) Product Group.

Exchange 2016 CU6 does NOT support.NET Framework 4.7 at this moment, and you should NOT install .NET Framework on a server running Exchange 2016. Not before and not after the installation of Exchange 2016 CU6. This is also true for Exchange Server 2013 CU17. More information regarding .NET Framework and Exchange server can be found here:

The .NET Framework 4.6.2 is supported by Exchange 2016 CU3 and higher and Exchange 2013 CU15 and higher. For a complete overview of which scenarios are supported, navigate to the Exchange Server Supportability Matrix on

KB articles that describe the fixes, features and information in each release are available as follows:



KB Article



Schema Changes

Exchange 2016 CU6






Exchange 2013 CU17






Source: jaapwesselius

Don’t Deploy Exchange Server 2016 on Windows Server 2016 For Now Due to Stability Issues

Since the release of Exchange Server 2016 Cumulative Update 3 (CU3), which added support for installing Exchange 2016 onto Windows Server 2016 servers, there’s been a series of reports in support forums and blog comments about errors that customers are seeing.

Now Microsoft has acknowledged that there is in fact a known issue, and there is no current workaround for it.

If you attempt to run Microsoft Exchange 2016 CU3 on Windows Server 2016, you will experience errors in the IIS host process W3WP.exe. There is no workaround at this time. You should postpone deployment of Exchange 2016 CU3 on Windows Server 2016 until a supported fix is available.

That’s all the detail that has been publicly released by Microsoft at this time, but the guidance is clear. You should deploy Exchange 2016 only on Windows Server 2012 R2 until further notice.