Sorry, this requires a bit of background.
We are looking to setup an abandoned cart email, which will be fired from collect.js tracking code on our website.
We currently use Salesforce CRM and Marketing Cloud. The subscriber key in MC is the ContactID from Salesforce. All our customers are stored as contacts in CRM. We also use the connector, so a portion of our customers are synced to MC. From there, we send emails to that portion and some don't receive it because they are Unsubscribed on the All Subscribers list - all good!
However, I am anticipating the scenario where a tracking event comes in from the website (for an abandoned cart) and the ContactID is not someone that exists on All Subscribers.
This is a problem because they have not opted in so we aren't allowed to send them an email. If they did exist, then MC would honour their subscription status. But in this scenario, MC default behaviour is to send them the email, add them to All Subscribers, and set them to Active - not good!
So what I would like to do is, for that particular journey, say "only send them an email if they already exist on the All Subscribers list" (MC will then decide to send based on their status).
Is this possible?