Please, makers of email subscribe and unsubscribe systems, stop allowing just anyone to supply any email address. That’s just asking for abuse. Stop putting your trust in random anonymous strangers.
What you should do when having someone subscribe: send a confirmation email to their address, with an expiring link.
What you should to when having someone unsubscribe: put an unsubscribe link into their email with a unique identifier that finds their subscription and instantly unsubscribes.
