Authority to examine newspapers, parcels or book-packets

The Postmaster General, or the district postmasters, may examine any newspaper, parcel, book-packet or other article, whether sent by the post without a cover or in a cover open at the sides or ends, in order to discover whether it is contrary in any respect to the conditions required to be observed, and in case any one of the required conditions has not been fulfilled, the whole of every such newspaper, parcel, book-packet or other article may be charged at letter rates.