End of sequence if the email is forwarded

The problem is this:

If "Client A" is enrolled in a sequence and he forwards me to "Client B" without answering one of my emails and then "Client B" answer me, "Client A" will still be enrolled in the sequence even if I'm dealing with "Client B". 


There's no workflow that enables us to put if "Client A" forward the email to someone that has the same email domain AND the email forwarded has an answer, unenroll the "Client A".