Here is a script to Send a message on Xbox 360
replace "gamertag" with the target profile name.
I've tested it and it works
This script was originally meant for a reprogrammed usb drive but i tested it on a USB rubber ducky instead.
DELAY 2000
WINDOWS r
DELAY 1000
DOWN
DELAY 200
DOWN
DELAY 200
DOWN
DELAY 200
ENTER
DELAY 2000
ENTER
DELAY 2000
ENTER
DELAY 2000
ENTER
DELAY 1000
STRING "gamertag"
DELAY 500
ENTER
DELAY 2000
DOWN
DELAY 200
DOWN
DELAY 200
ENTER
DELAY 2000
STRING this
DELAY 100
STRING message
DELAY 100
STRING was
DELAY 100
STRING sent
DELAY 100
STRING with
DELAY 100
STRING a
DELAY 100
STRING hacked
DELAY 100
STRING usb
DELAY 100
STRING drive
DELAY 100
STRING .
DELAY 100
STRING contact
DELAY 100
STRING me
DELAY 100
STRING via
DELAY 100
STRING phone
DELAY 100
STRING once
DELAY 100
STRING received
DELAY 100
STRING .
DELAY 100
DELAY 2000
ENTER
DELAY 2000
ENTER
DELAY 7000
WINDOWS r