Like Chris, I do this by sending an alert as well. I set this up as part of the flow. We wanted to CC messages going out to new leads to the assigned sales team member. So I set up the flow such that once the email goes out to the new lead, it subsequently sends an alert to the Lead Owner (i.e. their sales agent).
If you are sending a mass email, a seed list makes sense. But, for a triggered email, the Send Alert feature seems to work quite well.