\(\([a-zA-Z0-9]\([a-zA-Z0-9-]*[a-zA-Z0-9]\)\?\(\\\.[a-zA-Z0-9]\([a-zA-Z0
-9-]*[a-zA-Z0-9]\)\?\)\+\|[a-zA-Z0-9]\([a-zA-Z0-9-]*[a-zA-Z0-9]\)\?\)\(\
.[a-zA-Z0-9]\([a-zA-Z0-9-]*[a-zA-Z0-9]\)\?\)\+\)