New Features in Exchange Server 2016 CU6 (Part 1 of 2)

This is part 1 of the article.  See part 2 here

Starting with Microsoft Exchange Server 2013, Microsoft delivers hotfixes and service packs using a scheduled delivery model. Unlike a rollup update model used by previous versions, Exchange now receives quarterly cumulative updates, which addresses customer-reported issues and may include new functionality and/or features as well.

Within Exchange quarterly updates, Microsoft Exchange Server 2016 Cumulative Update 6 was released at the end of June. Along with fixes and compatibility updates, the new CU contains two new features: Sent Items Behavior Control and Original Folder Item Recovery.

Sent Items Behavior Control

One of the issues of granting send as or send of behalf permissions has always been where the sent item is stored.  Normally if someone sends a message as someone else, it is only saved in the sender’s mailbox.

Back in 2013, when Exchange Server 2010 SP3 was released, it added a new feature: “Set-MailboxSentItemsConfiguration”, that could be used to set where the mailbox server would save outgoing messages when someone used “send as” to send messages from a shared mailbox. It allowed saving the messages in sender’s mailbox or in both sender’s and shared mailboxes.

For example, let’s say you have a shared mailbox,, and a user, Aaron Apple,  Aaron has “send as” permission to the HR mailbox. If you have Exchange Server 2010 SP3 and you want the messages sent from Aaron using this shared mailbox to be saved in both sent items folders, you can use following PowerShell command:
Set-MailboxSentItemsConfiguration -SendAsItemsCopiedTo SenderAndFrom


Now, if Aaron sends any message as, it will be saved in both and

If you want to configure behavior for “Send On Behalf” you can use “SendOnBehalfOfItemsCopiedTo” parameter similarly:
Set-MailboxSentItemsConfiguration -SendOnBehalfOfItemsCopiedTo SenderAndFrom

In Exchange Server 2013, these Powershell cmdlets was replaced by instead using two new parameters of the Set-Mailbox cmdlet: “MessageCopyForSentAsEnabled” and “MessageCopyForSendOnBehalfEnabled”.

As good as this was, it was still not possible to configure this behavior to be applied to user mailboxes.  But an improvement was that these two parameters could control sent items behavior for shared mailboxes in both on-premises Exchange Server and Exchange Online. It was made to reduce the number of cmdlets and to allow configuring more mailbox settings with Set-Mailbox.

Now, one of the two new released features in Exchange 2016 CU6, “Sent Items Behavior Control”, allows these parameters to work with user mailboxes in addition to shared mailboxes.  As for Exchange Online users, this has been available since March 2017

For example, if you have users Aaron Apple ( and Barry Burrito ( .

Barry Burrito ( has “send as’ permission for Aaron Apple’s ( mailbox, and sometimes sends emails as him. If you want these messages to be stored in both Barry’s and Aaron’s Sent Items folder, you should set “MessageCopyForSentAsEnabled” parameter for Aaron’s mailbox to $true:
Set-Mailbox -MessageCopyForSentAsEnabled $true

To disable the message copying, set the same parameter to $false:
Set-Mailbox -MessageCopyForSentAsEnabled $false

And to check the feature’s status, use Get-Mailbox cmdlet:
Get-Mailbox | fl Name,MessageCopyForSentAsEnabled

The second parameter, “MessageCopyForSendOnBehalfEnabled”, works exactly the same way, but when someone tries to “send on behalf” permissions instead of “send as” permissisons.  To enable:
Set-Mailbox -MessageCopyForSendOnBehalfEnabled $true

To disable:
Set-Mailbox -MessageCopyForSendOnBehalfEnabled $false

And to check the current status:
Get-Mailbox | fl Name,MessageCopyForSendOnBehalfEnabled

This is part 1 of the article.  See part 2 here

Marat Mussabekov

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