..... you MUST have a valid working email address in your profile OR you need to turn automatic notifications, which tell you when someone has replied to one of your posts or sent you a PM OFF.
Each time one of these forum messages is generated and the email address isn't valid I get a bounce message. I understand people change email addresses of course but I'm getting so many each day now that I'm going to have to start disabling the accounts that are causing them.
Note that your real email address is not visible and not passed on to any third party nor used for any other purpose. It used purely to inform you of forum activity plus anything forum related that you may be subscribed to.