Exchange Connection Problems

Fix Exchange Online Error Executing Cmdlet for Send on Behalf

Adam Davis Oct 1, 2026 868 views

Question details

Users are unable to add a Send on Behalf delegate via the Exchange admin center due to a system error message.

Fix Exchange Online 'Error Executing Cmdlet' for Send on Behalf

Product: Exchange Online
Device & OS: not provided
Scenario: Attempting to add a user to the Send on Behalf delegation in the Microsoft 365 Exchange admin center.
Observed behavior: The interface displays an 'Error executing cmdlet' message, even though other permissions like Send As and Read and Manage are working properly.

Before you start

Ensure you have Exchange Administrator privileges and have the Exchange Online PowerShell V3 module installed to apply the command-line workaround.

Solution 1Recommended

Add Send on Behalf Permission via Exchange Online PowerShell

Since the error is isolated to the Exchange admin center interface, using PowerShell bypasses the UI glitch and successfully grants the permission.

This is the primary workaround while Microsoft investigates the user interface issue. You will need to connect to your Exchange Online environment via PowerShell to execute the cmdlet manually.

Connect to Exchange Online

Open PowerShell as an administrator and run the command 'Connect-ExchangeOnline'. Sign in with your global or Exchange administrator credentials.

Execute the Set-Mailbox Cmdlet

Run the command: Set-Mailbox -Identity "TargetMailbox" -GrantSendOnBehalfTo @{Add="DelegateEmail"} to apply the permissions manually.

Verify the Permission

Run Get-Mailbox -Identity "TargetMailbox" | Format-List GrantSendOnBehalfTo to ensure the delegate was successfully added.

Add Send on Behalf Permission via Exchange Online PowerShell

PowerShell Workaround: Using this method applies the exact same backend permissions that the admin center attempts to apply, effectively bypassing the UI error.

Solution 2

Contact Microsoft 365 Support

Because this is a known interface bug in the Exchange admin center, Microsoft support engineers need to collect tenant logs to permanently resolve the UI issue.

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Frequently Asked Questions

Why do 'Send As' permissions work while 'Send on Behalf' fails?

This is typically caused by an isolated sync bug or UI error in the Exchange admin center that specifically impacts the cmdlet tied to Send on Behalf delegations, leaving other permission cmdlets unaffected.

Do I need special permissions to run the PowerShell workaround?

Yes, you must be assigned the Exchange Administrator role or Global Administrator role in Microsoft 365 to successfully connect to Exchange Online PowerShell and run the Set-Mailbox cmdlet.

Will the PowerShell delegation show up in the Exchange admin center later?

Yes. Even if the admin center interface fails to set the permission, permissions assigned via PowerShell will correctly synchronize and reflect in the admin center UI and Microsoft Outlook.

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