In SFMC, each subscriber is assigned by the system a unique ID called the Subscriber ID. I've never really paid much attention to this field, but with the GA360 integration this field becomes the unique subscriber identifier for matching records with their Google Client ID.

It appears that subscriber ID's are numbers raised in sequential value. Does anybody know if:

  • When a contact is deleted, then re-added into the system, will they be assigned a new Subscriber ID or will it somehow re-pair them with their previous one?
  • If they don't receive the same Subscriber ID as before the deletion, are Subscriber ID's ever re-assigned, or will they always be unique (even across deleted contacts)?

Bonus points if this is documented anywhere.

1 Answer 1


Once a contact is deleted, the SubscriberID is gone forever. When you create the same contact again, they'll be assigned a new SubscriberID.

SubscriberIDs don't recycle.

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