I was reading about posting (mailing) items from United Kingdom to Switzerland with Royal Mail . https://www.royalmail.com/sending/international/country-guides/switzerland lists prohibited items
Here is an indication of prohibited items for mailing to Switzerland ... Vegetable products ... Explosives ... Printed books, newspapers, pictures and other products of the printing industry.
I can imagine why vegetables and explosives might not be permitted in the post (mail), but is it really illegal to post (mail) books and newspapers from United Kingdom to Switzerland?