If you don't know where its coming from, DO NOT open it! Its my rule of thumb, that ANY email coming to my account, whether in my inbox or bulk mail, and not from reliable or known sources is to be deleted without opening immediately. I only open emails from my friends and relatives, and even those, if they have strange subjects, I don't open them, because unfortunately these days emails can look like its coming from your friend but its actually a virus that infected their computer/email account, and then is automatically sent to everyone in their address book, so to be on the safe side, know what you're opening when you open it. I say delete it.