I cannot get Imessage to work on my IMAC, I have tried about everything.
Imessage on my IMAC will not let me send messages. I receive my messages but get Not Delivered on every message I attempt to respond to. I have tried about everything including, changing my Applid Password, disabling/re-enabling, rebooting, restarting, etc.
iMac 27″, macOS 10.13