Manually added members unable to unsubscribe

I’ve sent some test emails to members I’ve added manually and the emails are going through with no problem. However when I try the unsubscribe link (http://domain.com/e-newsletter/unsubscribe/82363eb0ad9bbbb3/) from the email I just get a 404 error.

I see other users have solved this problem by updating but I’m already using the latest version of the plugin so I don’t know what I can do to fix this…