Help Message Blocked Message

[Android Question]

Can someone help me everytime I text my cousin it says "Free Msg: Receiver 1323******* unable to receive message - Message Blocking is active." But I'm standing right next to them and neither of us have blocked each other and are still able to text other people its only saying that between us two any help?

 

[Hadron]

What says this? Normal in-phone blacklisting doesn't tell you that someone on the blocked list is trying to message you - why would you want that? So what is producing this message (presumably on his phone)? If it's a notification press and hold it to find out what app is producing the message. That will be a starting point to fixing it.