As far as I can see, there is nowhere that says that this email_sent_id is invoked by a campaign_id or a sequence_id.
This information can be inferred if the email’s batch_id is 0 and then you relate the timestamp of a step recipient (from a Keap report) to the timestamp of sending the email, but this can be as large as 6 minutes apart during peak times! It’s very unreliable!
Is there any way to find concrete relationships between an email that’s sent out by Keap and a campaign/sequence??