The first thing I would do is enable the response token for `profile.mboxtest` in the Administration tab so you can see the value in the response of the delivery calls.
Also, if you want the result to be sticky you might need to surround the code with a check of whether the profile variable has already been set, otherwise it might get wiped out on the next call if `person` is empty or not set.
if (!user.get('mboxtest') && mbox.name === 'target-global-mbox') {
return mbox.param('person');
}
or if it could later get set to something else, like `public` then
if (mbox.name === 'target-global-mbox') {
var x = mbox.param('person')
if (x) {
return x;
}
}