Behavior If the Same Email Is Sent Through a Smart Campaign and a Nurture Stream
Issue
You want to know the expected behavior if an email is sent to a lead from a Smart Campaign and then you add that exact same email (with the same email asset ID) to an Engagement Program nurture stream the lead is in.
Solution
The email will not be sent through the nurture stream, because an Engagement Program will not send the same exact same email to a lead twice, regardless of how it was originally sent. However, Marketo will send a cloned version of that email, since the email asset IDs are different.