First, note that Exhausted always shows up in the log before the final cast is actually sent (as you can see here). Interpret it as a Pre-exhaustion warning.
But you have to show us more of the EP setup here, and the people's send history, so we can prove/disprove that anything is unexpected.
I just received the emails in my inbox. Yesterday I was testing the same scenario and didn't received the email, so I was starting to get worried of what was going wrong.
thanks again for your quick reply and clarification that this is actually a Pre-exhaustion warning and not actually exhausted before the email went out