Unable to Save Delegation (Send As / Send on Behalf) Changes for Specific Microsoft 365 Group

Question

Hello,

I am experiencing an issue while managing delegation settings for a Microsoft 365 Group in Exchange Admin Center and am wondering if anyone has encountered something similar.

Environment

• Microsoft 365 Business Nonprofit tenant
• Exchange Online
• Microsoft 365 Groups
• Global Administrator / Exchange Administrator permissions

Issue

I am attempting to add a user (myself) to the delegation settings (Send As / Send on Behalf) of a Microsoft 365 Group.

The user can be selected successfully from the directory, and the Save Changes button becomes available. However, when I click Save Changes, nothing happens:

• No confirmation message
• No error message
• No warning
• The page remains unchanged
• The delegation entry is not saved

Troubleshooting Performed

1. Verified that I have the necessary administrative permissions.
2. Tested delegation changes on another Microsoft 365 Group in the same tenant.
3. The second group allows delegation changes and saves successfully.
4. Compared:
   • Group type
     • Membership
       • Ownership
         • Mail-enabled settings
         1. No obvious differences were identified.
         2. Changed the primary SMTP address of the affected group from an onmicrosoft.com address to a custom domain address and retained the previous addresses as aliases.
         3. Waited for replication and tested again.
         4. Tried different browsers and sessions.
         5. Verified that the user can be selected successfully in the delegation pane.

Additional Observation

This behavior appears to be isolated to a specific Microsoft 365 Group.

Other Microsoft 365 Groups in the same tenant allow delegation changes without issue.

Questions

1. Has anyone encountered a Microsoft 365 Group where delegation settings fail to save without generating an error?
2. Are there known issues with specific group objects becoming corrupted or having stale Exchange attributes?
3. Is there a PowerShell method to review or reset delegation settings for a Microsoft 365 Group when the Exchange Admin Center UI does not save changes?
4. Are there any Exchange Online logs that can help identify why the save action is failing?

Any suggestions would be greatly appreciated.

Thank you.

Answer 1

Use Exchange Online PowerShell to bypass the EAC UI and manage the delegation directly on the problematic Microsoft 365 Group.

1. Review existing Send on Behalf settings

1. Connect to Exchange Online PowerShell.
2. Run the following to see current Send on Behalf delegates:

Get-UnifiedGroup -Identity "<GroupIdentity>" | Format-List GrantSendOnBehalfTo

This shows whether any Send on Behalf delegates are already configured for that group.

2. Add or reset Send on Behalf via PowerShell

To add a delegate (for example, ******@contoso.com) as Send on Behalf on the Microsoft 365 Group:

Set-UnifiedGroup -Identity "<GroupIdentity>" -GrantSendOnBehalfTo ******@contoso.com

To clear existing Send on Behalf delegates and then re-add only the desired one:

Set-UnifiedGroup -Identity "<GroupIdentity>" -GrantSendOnBehalfTo $null
Set-UnifiedGroup -Identity "<GroupIdentity>" -GrantSendOnBehalfTo ******@contoso.com

This effectively “resets” the Send on Behalf list for that group without relying on the EAC UI.

3. Configure Send As for the group

To configure Send As for a Microsoft 365 Group, use Add-RecipientPermission:

1. Connect to Exchange Online PowerShell.
2. Run:

Add-RecipientPermission "<GroupIdentity>" -Trustee ******@contoso.com -AccessRights SendAs

This assigns Send As permission directly, even if the EAC page does not save changes.

4. Validate changes

After running the commands:

• Reopen the group in EAC and check Group delegation > Send As / Send on behalf to confirm the delegate is listed.
• Test by sending from Outlook or Outlook on the web using the group address and verifying the message shows the correct From / on behalf of information.

5. About logs and “corrupted” objects

The provided context does not document a specific “corruption” scenario for Microsoft 365 Groups or a dedicated log for failed EAC save operations. However, using PowerShell as above allows verification and direct manipulation of the underlying GrantSendOnBehalfTo and Send As permissions when the UI does not persist changes.

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References:

• Common management tasks for Microsoft 365 Groups
• Manage permissions for recipients in Exchange Online