How to Fix Delegates Sending Email As A User Not Being Saved To Sent?

Hi Overwatch Media

Exchange Online saves these emails only in the Delegate’s Sent Items folder. While there is a setting in the interface to change this one user at a time, your need to apply this to "all users in the whole organization" means the standard Admin Center is not practical. You can ask your Admin to use Exchange Online PowerShell (or Cloud Shell) to apply this setting globally.

To ensure that emails sent via Send As and Send on Behalf are saved in the Owner's Sent Items folder for every user in the organization, you can run the following bulk command in PowerShell.

This command selects all user mailboxes and enables the "Copy to Sent Items" feature for both delegation types:

Get-Mailbox -ResultSize Unlimited -RecipientTypeDetails UserMailbox | Set-Mailbox -MessageCopyForSentAsEnabled $true -MessageCopyForSendOnBehalfEnabled $true

This command applies the setting to all existing users. If new employees are hired in the future, the Admin may need to run this command again or include these flags in their new user creation script.

To confirm the settings were applied successfully, the Admin can run this command to view the current status:

Get-Mailbox -ResultSize Unlimited -RecipientTypeDetails UserMailbox | Select-Object Name, MessageCopyForSentAsEnabled, MessageCopyForSendOnBehalfEnabled

For your Admin's reference, here are the official Microsoft articles you can see:

Messages sent from a shared mailbox aren't saved to the Sent Items folder - Exchange | Microsoft Learn

Automatically save sent items in delegator's mailbox in Exchange Online | Microsoft Learn

Set-Mailbox (ExchangePowerShell) | Microsoft Learn

I hope this information helps and provides the necessary references. Please let me know if you have any further questions!

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Yes. Configure the mailbox so Exchange automatically stores copies of “Send As”/“Send on behalf” messages in the owner’s Sent Items, and optionally adjust Outlook’s delegate behavior.

In Exchange Online or on-premises Exchange, use Exchange PowerShell:

1. Connect to Exchange PowerShell (or Cloud Shell with the Exchange module).
2. For emails sent as the mailbox owner, run:

      Set-Mailbox <OwnerMailboxAliasOrUPN> -MessageCopyForSentAsEnabled $True
   

3. For emails sent on behalf of the mailbox owner, run:

      Set-Mailbox <OwnerMailboxAliasOrUPN> -MessageCopyForSendOnBehalfEnabled $True
   

After this, when a delegate sends as/on behalf of that user, Exchange saves a copy in the owner’s Sent Items. Depending on the Outlook client and registry setting DelegateSentItemsStyle, a copy may also be kept in the delegate’s Sent Items.

If further control is needed on the client side (classic Outlook only), the admin or user can set the DelegateSentItemsStyle registry value so Outlook decides whether to store the sent item in the delegate’s Sent Items, the owner’s Sent Items, or both. The server-side MessageCopyForSentAsEnabled/MessageCopyForSendOnBehalfEnabled settings remain the primary, supported method.

References:

• Messages sent from a shared mailbox aren't saved to the Sent Items folder
• Messages that are sent by using the "Send As" and "Send on behalf" permissions are copied only to the Sent Items folder of the sender in an Exchange Server 2010 environment