message notification after reading

It is essential to assign a color bubble that will allow us to say "attention," for example, Karine in green, Nathan in red, etc. I read a message; it is not for me; I put the color of the person concerned so that they can process the message, or else the message remains active until everyone has opened it. For example, if my boss is at the email address management@portal and he reads the message, I, being connected to the address secretairiat@.....il, should still see it until I open it.