Your due diligence lets you demonstrate the steps you've taken to do a proper job protecting personal data. Ask yourself how does any contact get into your list! If you don't know, you need to ask your supplier, you need to know the DNA of the data; and using your list over time means that you need to keep up to date with any changes to your list.
Ask yourself "How will I know if the data has been erased or rectified?" Make sure your supplier keeps you up to date - just ask how.
If you want a fantastic, responsive list, contact us. If you want to better understand how we keep you safe, see our Due Diligence Pack.