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.

These is the contacts I want to delete, because them not have the correct ContactKey

These is the contacts that have a correct Contactkey

1 Answer 1


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.

  • Thanks for your response Bill, Yes I know we need to add the Delay Registration to our SDK configuration, but during the team make it, I need to reduce the volume of contacts we have now. So my worried is if I delete these contacts, and some months next these customer log in the app, I have any problem, or simply I recieve a new contact with all the information (correct ContactKey, deviceId ...) in MKC? I don't find more documentation about it, except this [link](salesforce-marketingcloud.github.io/MarketingCloudSDK-iOS/… ) and not all is clear for me.
    – PviP
    Commented Apr 6, 2022 at 18:40
  • 1
    Deleting the contact won't cause any issue, but the contact will not be re-registered until something changes in the device/user registration: app update, timezone, contactKey, etc. CAUTION: many customers delete their contacts incorrectly using GDPR (right to be forgotten) which irreversibly disables them in our system. Seek services assistance.
    – Bill Mote
    Commented Apr 7, 2022 at 12:34
  • Thank you so much for your help! Now I have all more clear.
    – PviP
    Commented Apr 7, 2022 at 15:09

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