When the birthday or anniversary for a contact item is set an appointment item is created automatically. If the contact is removed those appointments are not. This article Find Outlook AppointmentItem for ContactItem
gave me the solution to remove those appointments. So that is great but I want to identify the “orphaned” appointments that where related to an already removed contact. Looking at the properties of a birthday appointment I found four properties that store contact information.

When the birthday or anniversary for a contact item is set an appointment item is created automatically. If the contact is removed those appointments are not. This article Find Outlook AppointmentItem for ContactItem
gave me the solution to remove those appointments. So that is great but I want to identify the “orphaned” appointments that where related to an already removed contact. Looking at the properties of a birthday appointment I found four properties that store contact information.