Is it permissible to work for a company that transports documents and parcels, knowing that it transports alcoholic beverages between countries, and may receive parcels from abroad containing prohibited items, and that the nature of the work involves solving problems related to transportation operations?

Working for a company that transports parcels is originally permissible, as parcel transportation falls under the category of lease (ijarah) that is permissible by consensus. It is a condition of lease that the benefit (manfa'ah) be Islamically permissible. Therefore, it is not permissible to transport alcohol or similar items. If the questioner's work will involve transporting alcohol, then it is not permissible for him to work for this company, unless he can avoid that.