iMessage spam seems to be a problem with some. Luckily, it hasn’t been a problem at all for us. However, if it’s enough for it to be widely reported, and for Apple to take a preventative measure, it must be an issue.
Now, you can put an end to that. Just take a screenshot of the spam message (press the Home button and power button at the same time. You will hear a shutter sound, and the screen should flash white for a second). After that, you send the image, phone number or email of the spammer and the time they texted you to firstname.lastname@example.org.
Let’s hope Apple puts a stop to most of these. It can become incredibly annoying.