Question around duplicate email in Journey Builder

Question

I have a question around this - I have a filtered data extension with product ID as primary key. The relationship is set to subscriber_key relates to subscribers on subscriber key.

Product ID	Subscriber Key	Email
ABCDEF	123456	[email protected]
BCDEFG	123456	[email protected]

If I were to use this DE in journey builder to send an email - will this subscriber be entered twice in the journey hence receive two emails? Or because the relationship is set to subscriber key, this prevents the journey from sending it twice and it will only enter once?

Answer 1

If the primary key of your data extension is set to Product ID and the relationship to the Subscribers' data is based on Subscriber Key, then each Subscriber will only enter the journey once, regardless of how many times their Subscriber Key appears in your filtered data extension.

Journey Builder evaluates the entry event's relationship to the Subscribers' data, in this case, the Subscriber Key, to determine whether a subscriber has already entered the journey. If a Subscriber Key has already entered the journey, it will not be re-entered, even if it appears multiple times in your filtered data extension.

Therefore, in your scenario, the subscriber with the email address "[email protected]" will only enter the journey once, regardless of the fact that they have two product IDs associated with their Subscriber Key in your filtered data extension.

Thanks