I have a mobile app with an android SDK to be able to send push notifications from the Marketing Cloud. Each user who installs and registers in the app must receive a specific ContactKey determined by us, for example their email. I have a large number of records in All Contact that do not have the email but a token in ContactKey, I understand that, since they have not logged in, they have not managed to associate the device Id with the email as contactkey. My question is, if I can delete all the records whose ContactKey is not the email and, if at any time those users log in to the application, it will give me a problem. Because I exceed the number of billable contacts and I need to delete these. Many of them have been like this for years.
Best Answer
You should use Delay Registration Until Contact Key is Set if you wish to only register "known" devices/contacts. This will keep the SDK from registering the contact until the user is known.
You would need to contact support if you want them to delete contacts based on some criteria, but deleting them won't be enough as the SDK will simply re-register them until you also update your application with the aforementioned setting.