We have connected above clouds using v5 Marketing Cloud Connector, and everything is working fine, when er are using the Account ID as Subscriber Key. We can both send emails, and tracking is successfully sent back to Salesforce.

We are working in an enterprise landscape, where we need a common ID across all systems, and until now, we have been using Contact ID for this. However we are looking into switching into using a custom ID instead. If we are to keep using Marketing Cloud for sending out transactional emails, this ID should also be used as Subscriber Key, qua the need for including this in API calls triggering transactional email.

However, when testing using this custom ID as Subscriber Key, we are not able to receive tracking back into Salesforce, on individual level. Only aggregated email results are available. Is there a way of changing which ID should be used as subscriber key?


You must understand the relationship between the DataExtension(DE) which holds the contacts of the MC Connector and the 'All Subscribers' list.

It is as any other DE relationshinp, the subscriber is created under All Subscribers when an Email is sent.

We faced a similar issue in another project, what we did was to create another DE (lets call it CustomDE) with the same fields as the MC Connector, then we populate it on a daily basis using a 'Query' and 'Automation Studio':

  • This DE has a relationship with Subscribers based on a custom field (custom ID) equals to the MC Subscribers 'Subscriber Key'.
  • The query overwrites all the rows of the CustomDE with all the contacs from the MC Connector DE (SELECT * FROM ')'.

We use that customDE to send emails/SMS/Push and SOAP/REST api.

Hope it helps

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  • Thanks @SebOB -Let me see if this will work in our environment – Lukas Lunow Dec 20 '16 at 9:20

Salesforce Marketing Cloud Connector only supports sending emails to Contacts or Leads, if tracking is to be synced back to Sales Cloud:

Ensure that email recipients are pulled from a Salesforce campaign, report, contact, lead, or person account. Marketing Cloud Connect does not support sends to objects other than Lead, Contact, or Person Account. If the email send is using a Salesforce data extension, ensure that the subscriber key is an 18-digit Contact or Lead ID.


Hence custom ID as Subscriber Key is not supported OOB.

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