I turned off iMessage due to security and I'm not receiving any messages. And nobody knows about it!

Im having a similar issue, nothing to do with security but in the past I would be able to turn iMessage off and receive all messages as SMS. Now when I turn iMessage off people try to message me the messages are just lost and neither party gets notified I would really like the option to have it back to how it was before

Only the sender of the message has the option to send the message as SMS if it cannot be received. The location for this is at Settings > Messages > Send as SMS. The reason why the sender is in control of this is that messaging rates may apply when sending a SMS message and there is never any charge for sending an iMessage. If the receiver of the message could force the sender to send them as SMS, then the sender could be faced with charges for the message that they did not want to incur by sending them as iMessage.

Another thing is that if the sender has Send as SMS shut off and they sent you an iMessage that you cannot receive, they will get a Not Delivered error, so they know that you did not receive the message. They could then choose to call you or send as SMS if they wanted to.

To be clear, there is not a zero-click RCE Exploit in the wild affecting users. What has occurred is some guy on the Dark Web has claimed he has one and is selling it for $2 million dollars. There is no confirmation that it is even true and no one is going to send $2 million dollars to someone based on this claim. I have seen many more unbelievable things for sale on Facebook Marketplace

RobaloAmigo wrote:

I have checked it and sender of iMessage see status "Sent", not "Not Delivered" so sender is not informed about my unavailability! That's the issue I am writing about. In the meantime I have probably discovered root cause of issue. I have also Mac and noticed today that iMessages were enabled and delivered to it. But I am using my Mac once per week! I don't believe that iMessage function is so stupid that it cannot detect that I didn't read iMessage for long time and don't suggest me to turn off this function also on Mac. This setting should be synchronized between devices!

If you have multiple devices using the same Apple ID the sender will still show Sent because it was Sent to your Apple ID and you still have a device using iMessage. When using iMessage it uses your Apple ID not your phone number. The iMessages are synced between devices but only when the service is on. Yes, you would have to have turned off iMessage on your Mac also, then the sender would see Not Delivered. SMS is sent to a specific device and iMessage is sent to your account. SMS can occur charges based on your cell provider, iMessage will not.

So in your situation, you have one device using iMessage and the other is not, but you still want to get notified that an iMessage was sent to another device. It does not work that way, either you use iMessage to get the message or shut it off and you won't get it. Remember they are not sending it to your phone number, they are sending it to your account, and you have chose on one of your devices to not see it.