If he knows it is haram, he must not deliver it and he will be sinful for that. But if he can’t know, there is no sin on him,

If one has a job delivering packages and sometimes the packages may or may not contain chocolates which include alcohol, is this job haram for him? Also, there is no way to tell what is in the package because they are not marked and are being sent from business companies not by individuals. Is one sinful if he does not know what is in the package but he knows there could be a possibility of something haram being in it?