Spam Spam Spam Spam...

This is kind of weird, and I don't know quite what's going on... I've gotten three pieces of apparent Spam this morning, but all came in as "Returned Mail: User Unknown" from the Mail Delivery Subsystem. (Yes, I use Outlook Express. So sue me.) Attached are emails that appear to be the usual garbage. Is somebody running some sort of spoof, and is this new or am I just seeing it for the first time?