Is it permissible to benefit from a package of unknown sender that arrived addressed to the recipient with their name and address, knowing that its price was paid by someone else?

The prevalent assumption is that the package is sent to the inquirer, and knowledge of the sender is not a prerequisite for accepting a gift. If the inquirer wishes to be cautious, he should inform the website administration of his suspicion and keep the package for a year. If no one contacts him regarding it, he may then dispose of it in a way that benefits him.