NOTE: This behavior will be changing soon. Please see the 'announcements' section of this help center for more information.
When a petition signer is contacted by the campaign creator, the email includes the option to unsubscribe. However, unsubscribing only stops the signer from receiving emails about that specific campaign – they will remain in the parent organization's CRM system.
Likewise, if a signer is contacted by a partner organization and chooses to unsubscribe, they will be unsubscribed from the partnership, not from the parent organization's CRM.