Resolve reported issues with shared mailbox Sent Items folders (IT support staff)


Introduction

On June 3, 2021, the Digital Workplace will implement an improvement that modifies the way sent messages are filed in University of Toronto (U of T) shared mailboxes if sent using the Outlook for Windows desktop application. While this modification is beneficial and seamless for most users, it may cause minor email display issues for U of T users whose machines have been previously configured by their local IT divisions. If your client reports an issue with duplicate emails in the Sent Items folder of their shared mailbox, please follow these steps.  

Note: Background information on this change can be found in this knowledge base article on changes to the shared mailbox sent items folder.

Digital Workplace clients

Digital Workplace clients who experience issues with duplicate emails in Sent Items after the implementation of this change should submit a ticket through the Enterprise Service Centre’s Get Help form. However, the removal of the group policy previously applied to Digital Workplace-managed machines (the old UTORcsi network) will be coordinated with the implementation of the new server-level changes, meaning the change should not disrupt Digital Workplace clients. 

All other clients

Individuals reporting that their sent messages are being duplicated in the shared Sent Items folder should identify which machine they are using when this occurs, as the issue is a device-specific configuration. Fixing the issue will require either a network-level (GPO) or local registry change. 

Network-level GPO change 

GPOs are used to manage groups of Windows machines (I.e. managed desktops). GPOs can only be edited by the network system administrators and will affect all joined machines.  

The following procedure is intended for network administrators managing GPOs. 

  1. Locate the GPO in your environment that controls where shared Sent Items are stored. 
    • Key Path: Software\Microsoft\Office\16.0\Outlook\Preferences  
    • Value Name: DelegateSentItemsStyle
    • Note that Office version “16.0” refers to Office 2016 and up, including Microsoft 365. If you are running older machines, the version number will be different.
  2. Check whether the GPO also contains other changes (such as modifying where shared Deleted Items are stored). If so, replace the combined GPO with new GPOs that handle the registry items separately before proceeding.
  3. In the GPO containing DelegateSentItemsStyle, select the Common tab and ensure that the option “Remove this item when it is no longer applied” is checked.
  4. When you unlink the GPO, the registry change will propagate out to all joined machines.  

Local registry change 

Note: The server-side change to Sent Items will not affect regedits applied for the Deleted Items folder. 

This is a change made directly on a specific Windows machine reporting the issue. 

CAUTION: Modifying the Windows registry incorrectly can cause serious problems. As a precaution, you may wish to back up the registry before proceeding (see: How to back up and restore the registry in Windows). 

  1. Open Registry Editor by clicking Start, then Run, type regedit, then click OK. On Windows 10, Registry Editor can also be found in the Start menu underneath Windows Administrative Tools.
  2. Navigate to the following subkey:
    • HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences 
    • Note that “16.0” refers to Office versions 2016 and newer, including 365. To find the correct version number for older copies of Office, open Outlook and look at the About info (typically under the Help menu). 
    • If you are running regedit as an administrator, ensure that you locate the subkey under the correct user profile.
  3. You should see DelegateSentItemsStyle set to 1. Right-click on it and select Delete.
  4. Exit Registry Editor.