shadowfamily.com according to google cache was a site related to carders
theplanet.com is a large hosting co. that used to host a large amount of spammers in the past. Probably someone is getting a lame revenge.
I haven't seen the email headers, but i'm very sure it relies on proxies. Close to impossible to trace who really sends it. It has been happening for some time now if you check the
usenet
i would say just delete it