So something like this:
preg_match( "/[a-zA-Z0-9]/!/@/$/_/=/-/+/\s/", $msg )
Updated it: preg_match( "/[a-zA-Z0-9]!@$_=-+\s/", $msg )
I found this on your first link. It is useful and clear.
I am now using this:
preg_match( "/[a-zA-Z0-9]!@$_=-+\s\h\v\H\V/", $msg )
it still doesn't accept...