I use Lead Id and Account Id (for converted leads) as the main subscriber key, but there are some cases where they might use Contact ID as the key.

These Id values are different in Sales Cloud for a given user - but would the system recognize that it's the same person if they use both Account and Contact ID? Or would there be separate records/people in All Subscribers?

And when a Lead is converted to an Account/Contact - does the system create a separate record for them because the ID values are different?

1 Answer 1


If you want to utilise the standard functionality for Marketing Cloud connect (e.g. tracking data integration), you should only use Contact or Lead ID as subscriber key - not Account ID. A single Account ID might also cover more than one contact.

There is currently no ID that links these different IDs together, if they belong to the same individual. Also in cases where a lead gets converted to a contact. The newly created contact ID will not hold any of the engagement data, previously collected for the lead ID. MC will see these as two separate individuals.

There is only a single case, where this data gets migrated, and it is when converting a lead in a Journey Builder activity. However this is very rarely used, as most conversion logic usually sits in Sales Cloud.

  • This is highly interesting. Does this update the contactkey to the generated lead id or does it migrate engagement data to the new lead record? Commented Mar 16, 2020 at 18:43
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    I just took the time to test this and would recommend never using the JB Lead Conversion Activity. This basically just populates the _ContactKey field in synchronized data sources for the newly created Contact with the original Lead Id. This now binds the synchronized Contact to the original Lead Id. The big issue is: All other types of MC Connect integrations will still use the the normal contact id field: e.g. Journey Builder Sends and Sends to Reports/Contacts create a new Contact in Marketing Cloud based on the Contact Id, which now is a duplicate of the converted Contact. :( Commented Mar 21, 2020 at 12:11

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