Short description of Actual Contacts for Outlook 2.3: Actual Contacts for Outlook is a Microsoft Outlook add-in for validating and updating your address book. Select contacts and ACO will send them a message containing a form. The respondents will be able to update the data in your address book by filling out the form and sending it back to you. E-mail addresses in your Microsoft Outlook address book can be verified with just a few mouse clicks.