Is there a ACS Campaign API that will tell you someone unsubscribed and what email they unsubscribed from?
The following link gives some insights around fetching Unsusbcription details using API:
Apart from this, the below link gives some reference about fetching Subscriptions in ACS, not sure if Unsubscriptions would work in a similar manner:
Adobe Campaign Standard API
Can you find out from your Adobe Team if this is possible?