I had a same problem (9230 message, invalid destination ) when I was trying to send text message. but it is fixed now after I cleared the dialer (setting -> application -> manage application -> dialer -> clear data. Also clear all the text messaging history. My phone is HTC EVO 4G, not the iPhone, but I have seen this problem on the Samsung Galaxy, and other phones too. Just wanted to share - good luck!!!
This started for me after I reset my daughter's phone. I have specific text blocking setup for her number on the sprint account. I found that imessage and facetime were trying to activate.
I disabled imessage (point of blocking text messages) and lifted the block on the sprint account until facetime activated, then reblocked the text messaging with Sprint.
I hope this helps.
On my iPhone 4S I am getting texts several times a day that says "The recipient you are sending to is in your block list. You have chosen to block all texts from (and to) this recipient. Msg 2134" I am not sending any texts to anybody. This has happened several times in the past few weeks, but not every day.