We are currently using Marketing Cloud Connect to connect with SalesCloud, our Subscriber Key being the SalesCloud Contact ID. We sometimes receive lists of email addresses we need to send to that may not be in SalesCloud, so no Contact ID to use as the Subscriber Key. What are the cons of sending to these lists? Would the ramifications be anything worse than possible duplicate contacts/messy data?

2 Answers 2


It's a classic conundrum unfortunately. There are several issues to consider:

  • Duplicate/messy data (as you've already noted)
  • Compliance - you'll need an additional process in place to ensure an unsubscribe is honoured across multiple subscriber keys in the event you have duplicate email addresses (this is straightforward to do but needs to be done)
  • Cost - you'll be paying for each subscriber you store in Marketing Cloud
  • Tracking - once you have duplicates, you'll have differing engagement history stored against each subscriber
  • Archiving/removal - you'll need to factor in that there may be multiple subscriber keys associated with a single email address, so will need to adapt your process

However, in many organisations it's simply not practical to import all data into Sales/Service Cloud. I'm assuming that you/your organisation don't want these extra email addresses stored in Sales Cloud? If so, then as long as you have remedial action ready for the above considerations, you should be clear to send from Marketing Cloud.


What is the reason for not storing them in your Sales Cloud?

Do you have MDM in place?

I would personally never recommend a customer to upload customers through csv file in SFMC if there is a CRM available, mostly for all of the reasons Antonio already mentioned. However, I would also say that SFMC is not a mailchimp, it's too expensive toy to manage your database through csv when you have CRM available.

I am speaking from experience. Once you have thousands of duplicated records your job will get harder as Antonio mentioned and if you are on a budget SF will charge you double for duplicate contacts.

If customer A exits in Sales Cloud with COntact ID, you get charge for him. If you bring him to SFMC with some other SK, once you send him first email, from SFMC perspective he is recognised as other customer because SFMC is looking at SK, not email address.

A bit more information on your data strategy and reason why those customers are in csv and not in Sales Cloud would help us to give you strategic recommendation as well.

  • the reason for not storing in our SalesCloud is because the SalesCloud has a specific purpose and contacts/leads are loaded with specific criteria. The lists we get for some sends don't meet these criteria. Dec 4, 2020 at 20:23

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