To resolve this issue, you need to terminate the pending processes. 

1. Close Outlook.
2. Go to Start > Run, type “taskmgr” and then click OK.
3. Go to the Processes tab.
4. Look for all the processes named as “Outlook.exe” and then click on End Process.
5. Close the Windows Task Manager.
6. Go to Start > Run, type “services.msc” and then click OK.
7. Look for the Trend Micro Client Server Security Agent Listener Service, right-click on it and select Restart.
   Note: The name of the service may vary depending on the product.
8. Close the Services window.
9. Open Outlook again and verify that the Antispam toolbar is now available.

If the issue persists, contact Trend Micro Technical Support.