There are a lot of emails that come through that try to sucker you into something. Unless I know the sender, it gets deleted usually by my providers spam controller or by my email software. Anything that my provider or my software has label as suspicious I simply don't open. I still use the older Netscape v7 for my email so opening it doesn't activate anything in the email like Outlook does so I can look at the From, To, Date and Subject without executing any viruses. Typically I open my mail files in notepad and check them for flaws which can tell me if its fake or not. Just takes some extra steps but it's worth going the extra step. And there are more than just cards without a sender's name, they are trying many more things.
I also used to send all the emails to [email protected] or [email protected] since those are the departments that are suppose to take care of them. But I easily found out they simply send you two automated responses and delete the emails you sent them. They don't have the manpower or give a damn that their customers are getting hammered with fake emails. So they don't bother to take any action so I don't bother telling them anymore. I even reported a customer that sent me a pyramid scheme in a shipment and they didn't do a thing.