Why Deprecated Outlook Add-ins Keep ReappearingMany legacy add-ins remain integrated into modern Microsoft 365 Apps and Office C2R (Click-to-Run) installers:
UcAddin.LyncAddin.1 (Skype for Business / Lync Meeting Add-in): Microsoft maintains a single shared binary footprint for enterprise builds. Because on-premises Skype for Business Server is still supported in hybrid corporate deployments, the C2R updater frequently restores missing registry registrations during standard updates or repairs.
OscAddin.Connect (Outlook Social Connector / People Pane): Originally built for Facebook, LinkedIn, and SharePoint integration (which Microsoft retired years ago), the OSC component (SOCIALCONNECTOR.DLL) is still bundled in the standard Office core binary package.
Simply unchecking or deleting these entries inside Outlookâs COM Add-ins UI often fails because the Office update engine evaluates default registry paths on restart or update cycles and sets their LoadBehavior back to 3 (Load at Startup).
How to Permanently Disable or Block ThemMethod 1: Disable via Registry (LoadBehavior = 0)Setting LoadBehavior to 0 leaves the key intact so the Office installer stops re-registering it, while telling Outlook never to load the DLL at startup.
Run the following commands in an elevated Command Prompt or PowerShell:
:: Disable Skype for Business Add-in (User & Machine level)
reg add "HKCU\Software\Microsoft\Office\Outlook\Addins\UcAddin.LyncAddin.1" /v LoadBehavior /t REG_DWORD /d 0 /f
reg add "HKLM\SOFTWARE\Microsoft\Office\Outlook\Addins\UcAddin.LyncAddin.1" /v LoadBehavior /t REG_DWORD /d 0 /f
:: Disable Outlook Social Connector (User & Machine level)
reg add "HKCU\Software\Microsoft\Office\Outlook\Addins\OscAddin.Connect" /v LoadBehavior /t REG_DWORD /d 0 /f
reg add "HKLM\SOFTWARE\Microsoft\Office\Outlook\Addins\OscAddin.Connect" /v LoadBehavior /t REG_DWORD /d 0 /f
If managing machines via GPO or Intune, enforce the policy key to disable the Social Connector entirely across the organization:
Registry Path: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\Outlook\SocialConnector
DWORD: RunOSC
Value: 0 (Disables the Outlook Social Connector completely)
For clean machine deployments, exclude Skype from the initial install footprint inside your configuration.xml:
<Configuration>
<Add OfficeClientEdition="64" Channel="Current">
<Product ID="O365ProPlusRetail">
<Language ID="en-us" />
<ExcludeApp ID="Lync" />
</Product>
</Add>
</Configuration>