I strongly urge you to change the ridiculous policy of allowing someone who receives a forwarded email from one of my members to be able to unsubscribe the original recipient. This makes no sense at all. A solution would be to send an email to the original recipient asking if they wanted to be unsubscribed. I know you can do this because you have the ability to block the email address of the original recipient.
I only know this is happening when I myself am unsubscribed, but it has happened 3 times now. I urge you to protect Constant Contact's reputation by stopping this dumb policy that only gets your users frustrated.