I'd like to add contacts to a marketing list based on whether or not they open an email in a journey. My goal is to have a trigger that evaluates if the email was opened or not. If it was not opened, I'd like to add them to a separate, 're-engage' list for a future campaign. This list would be part of the subscription list these members have already consented to, so there should be no GDPR issues.
Is this possible? I don't see a block that would accomplish this in the journey builder.