SAP How to send popup message to a specific user

How do you do that? By running a function module!!
SM02 sends messages to all users, not a specific one
So use function module TH_POPUP
goto Transaction code SE37 enter the function module name & test run it
the the resulting screen is shown below, type the details and execute
The the user will see message like this ( System name is blurred for privacy reasons)


The user must be logged into the system to receive the message