HOW DOES THIS WORK?
When you have this feature enabled in the dashboard, PieSync detects your unsubscribes on one side of your sync and adds a tag/folder/list/group/...(app dependent) on the other side of the sync, named 'PieSync Unsubscribes'. You can then manually check this new subset of contacts, to see if you actually want to unsubscribe them there as well.
We choose not to automatically unsubscribe or delete the unsubscribed contacts on the other side, as we want to empower you, the end user, with taking the final decision on whether to delete the contacts forever, or to restore them. The 'PieSync Unsubscribes'...tag/folder/list/group/...(app dependent) allows you to do a double check before doing any unwanted damage with just a small manual action.
WHEN IS THIS AVAILABLE?
The availability of this feature is app and connection dependent, but you'll see it come up with marketing apps mostly. If the feature box (screenshots above) is not there to tick, it's simply not possible. We need to be able to detect unsubscribes on one side and at the same time be able to create a tag/folder/list/group/...(app dependent) named 'PieSync Unsubscribes' on the other side. When available, we always explain how and in what direction this will work for that particular connection (see example above between Google Contacts and MailChimp).