Sending triggered emails via the SOAP API results in duplicate subscribers being created

Question

We are having problems with Salesforce Marketing Cloud. Here is our scenario:

1. A subscriber is created via the user interface (with the email any subscriberkey set to the same value)
2. A triggered email is sent to the email address and subscriberkey noted above (note: no call is made to upsert a subscriber, just a TriggeredSend request

Within the MC UI, we see 1 subscriber in the All Subscribers list. From the API, we see 1 subscriber in the All Subscribers list.

However, if we extract the _Subscribers table (using a query activity, data extract and file transfer) to a file and examine the contents, what has happened in reality is:

1. One subscriber was added when we added the entry via the UI (with subscribertype = 'ExactTarget')
2. A second subscriber was created, with a different subscriberid, but matching subscriberkey and emailaddress with subscribertype = 'Unknown External System'

Has anyone come across this problem before? It is affecting us in a big way (many many duplicate contacts) and in the case where there are duplicates, there can be differences in the subscriber's status (i.e. one subscriber can be listed as active and one as held or unsubscribed) which we are really concerned could be the cause of some unexpected email send behaviour.

We've tried forcing the subscribertype to ExactTarget when we interact via API but this seems to have had no effect.

Welcome any thoughts on what we could be doing wrong here.

Answer 1

Unknown External System is also referred to as the 'Triggered Send Managed List'. You are correct that it is separate from the All Subscribers list which you see in the UI. In order for your Triggered Email subscribers to utilize the All Subscribers list instead of the Triggered Send Managed List, a list needs to be selected in the Subscriber Management section of the Triggered Email Definition (Interaction > Triggered Emails in the UI or the TriggeredSendDefinition object in API). After making a change to a Triggered definition so that a list is selected, make sure to publish the definition so the change is active.

In the Subscriber Management section, you would see lists that you have created in your account and should also see "All Subscribers" as an option. If you don't want to create a list for this purpose and don't see All Subscribers as an option, then contact Global Support and they can enable the option in your account so that All Subscribers is available to select there.