To add a "ping" notification to a message

To add a "ping" notification to a message that you sending to let them know you need attention from him/her

To add a bell icon next to the "Send later" in the message field, when sending a message to someone, when this icon is activated, the receiver will see a bell icon appeared on his end on the space list for the message, that his urgent attention is needed. This feature should also comes with a sound to increase the attention from the receiver.