Just adhere to these instructions.
Some carriers may include a different app for messaging.
You would have to use an app like SwiftReply, mentioned below.
If your messaging app does not offer a Blacklist option, use Handcent.
Now all of the text messages from that person will be blocked and not visible in the Handcent app.
You wont get notifications youve received a message from the person either.
Some users have reported that the app Private Space works well for them.
I recommendSMS Auto Reply.
The app will allow you to setup an auto reply for specific Contacts.