I got the e-mail as well. Used my secured browser (IceCat, NoScript, ABP, RequestPolicy, &c.) to try to log into their phpBB forums. First thing I see is a "Logout" link, every link URL on the page has a "?sid=abcd1234" style parameter on the page. I try to use the Contact link to tell them (Clem?) about this, get the error "You cannot send any more messages". Try logging out, but the contact form require login. I don't remember my own login, and the password reset link sends me a password by e-mail in plain text. Also, it doesn't work. TL;DR: Don't trust the Linux Mint forums!