Hi,
Very exciting scenario.
Short version:
Firstly, you are using the “marketing” option for your email. Don’t do it in this case, cause you actually have a transactional email.
Secondly, if a person leaves the campaign (finished the last step) can be readded by leaving and re-qualifying for the segment. You have to make sure you turn on the switch by campaign ‘Can restart campaign’.
Long version:
I have a long blogpost about this with screenshots and different tests. If you have nothing better to do, read it, you can really understand how this works: