one of our client uses Content Builder Send flow (for one shot email) to send his emails. He wanted to use a Salesforce Data Extension as target DE for his send, and a DE from the Data Extension folder as Excluded Data Extension.
Once he selected the Salesforce DE, the "drag and drop" of the Excluded one (from the Data Extension folder) didn't work, it was blocked.
Is there a reason why ? Does the Excluded data extension has to be in the same folder as the target DE, and in our case the Salesforce DE folder ? Actually, if we choose a Salesforce DE as Excluded DE with a target Salesforce DE, it seems to be possible.
Also, could you confirm that for the exclusion to work, the excluded DE needs to have the same Subscriber Key than the target DE ?