Our company is using Marketing Cloud to trigger automated transactional emails via API for emails like order confirmation, email address verification, password reset etc...

As per the MC guide for developer, we've created subscriber lists for each, where the email address is added when the email is triggered.

However, doing so adds the email address to our All Subscribers list and ultimately creates duplicates. That's the case if the email address is an actual subscriber already in this list or if the user later creates a profile in our website. In both cases they are first created in Sales Cloud and imported via the synchronised data source to MC and the All Subscribers list. So, at the end, the duplicate email address from these triggered emails co-exists along with the "good" email we're using, linked to Sales Cloud.

FYI - We didn't create "Triggered Sends" in MC - Our developer just built send definitions with the API and we're using the email templates within email studio

Is there a way to avoid these email addresses to be created or at least added to the All Subscribers list when a transactional email is triggered?

What I've read is that we probably need to create a "Triggered Send" in MC and uncheck the "Add subscribers to this list" box. Is that the correct/best way to proceed? If so, is there any risk or impact not adding the subscriber to the list?

Many thanks for your help,


  • if you are using the same SUBKEY how is this process creating duplicate contacts?
    – EazyE
    Jun 15 '20 at 16:37
  • Hello, we are not using the same subscriber key. The email created via triggered send is not added to Sales Cloud, we're using the email address as the subscriber key. While the email created via a subscription method is added to Sales Cloud and has the ContactID as the subscriber key.
    – Aurelien
    Jun 15 '20 at 17:31
  • Sorry, what do you mean?
    – Aurelien
    Jun 15 '20 at 17:51
  • No matter the configuration these would still be added to a list (ALL SUBS or Triggered Send Managed List) and be counted as a contact
    – EazyE
    Jun 16 '20 at 21:30
  • Yes, that's what Salesforce support confirmed. So basically there's no way to avoid those duplicates from triggered sends and they'll have to be deleted afterwards. thank you
    – Aurelien
    Jun 17 '20 at 12:08

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