While under normal circumstances most users would never see an unwanted or "spam" message in the OS X and iOS program Messages, Apple has now set up abuse reporting mechanism to help deal with those who have the issue. Using the email address imessage.spam@icloud.com, users can send a screenshot of the unwanted message, phone number or email address of the spammer or harrasser, and time/date info on the message. Unwanted or spam SMS and MMS messages should still be reported to users' cellular providers rather than Apple.
