You receive this message, because DTL Outlook COM add-in is installed on your computer. The plugin is a Outlook tool developed by Domain Technologies that will help you to manage a large volume of emails. If you want to remove it, launch Outlook and from the Tools menu select Trust Center. Click the Add-ins option from the left, press the Go button next to COM Add-ins and un-check the box next to DTL Outlook COM. After that, go to Control Panel > Uninstall a program and remove the application.