We are doing an exercise to clear contact count and noticed that one of our BU has more than 500k subscribers against our Mobile Push Dev App. What could be the plausible reason for this huge number? We dont have any journeys running sending Mobile Push notification, nor any import automation i can find.

Has anyone else faced the same issue, this 500k numbers is definitely not organic as we only have around 200-300k legit Email/SMS subscribers? Could there be an API or Mobile SDK setup?


  • There is not enough information to give feedback, but this might be coming from the app. I would check how it is pushing contacts to SFMC and double-check the contact keys format of these 500k in SFMC (GUID or "normal")... Commented Nov 23, 2023 at 8:18
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    First of all, clear up with the app developers if "Delay Registration Until Contact Key is Set" (salesforce-marketingcloud.github.io/MarketingCloudSDK-iOS/…) method is being used in the SDK. If it's not then then contacts are registered first with random ID (the GUIDs mentioned by Rachid) and then with a proper ContactKey once it is obtained - this way each installation would create 2 contacts or more (each app install generates a random ID - even across multiple installations on the same device) Commented Nov 23, 2023 at 10:17
  • Thank you Rachid and Rafal for your response, I checked with app team, "Delay Registration Until Contact Key is Set" is true. I will investigate this further with them. I am no mobile app expert, but does it matter if app team is using production APNs .p12 Certificate for the Dev App?
    – parleggirl
    Commented Nov 28, 2023 at 2:09

1 Answer 1


Found the root cause, unfortunately our mobile app dev team used the SFMC AppID of one of our BUs (divided by countries) across all our other BUs without realizing they need to use a different SFMC AppID for each BU. This raked up these numbers.

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