Can you turn off imessage and see if that prevents them from sending them using that method?
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Thank you Ann154 for assisting katie412! iMessages can not be blocked! The only way to stop that user from sending you messages is by placing them on the Call & Message block list and turning off your iMessage app. To turn off, go to settings > messages > iMessage > Off.
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