Linked: iCloud Spam

In Apple’s Mail application, you should forward these junky missive as attachments to spam@icloud.com. To do this in Mail, just select the message and choose Message > Forward as Attachment. This generates a new email message that includes an attachment. This attachment contains not only the contents of the message, but also its headers—the information that details the Internet path the message took to reach you. Apple uses this header information to filter out future messages sent from this vile domain. – Macworld

Genius.