How can I stop SPAM messages on my iPhone?

Block, filter, and report messages on iPhone

1. In a Messages conversation, tap the name or number at the top of the conversation.
2. Scroll down, then tap Block this Caller.

Block, filter, and report messages on iPhone - Apple Support (IN)

Blocking caller in imessage doesn't work because as soon as you open the message, they will send more messages under different numbers. Is there another way to BLOCK SPAM MESSAGES? My imessage is blowing up and it's very time-consuming. I've deleted without opening, I've blocked them, I've replied STOP--it only perpetuates more messages. Also if i delete on my iphone without opening the message--it still exists on my macbook imessages and the only way to delete the conversation is to open it first. Once they see it's been read they just send more. Surely Apple can figure out how to block bot numbers?

You may --> Block unwanted callers in FaceTime on iPhone - Apple Support