How to recognise unauthorized opening of our letters? Trassological additions to recognise check-up of a letter

Abstract

The author of the following lines spent a few months in a capitalist country for exchange of experiences and now announces his experiences gained at regular observance of his post. During the time of observance (one and a half months) I had the opportunity to check eighteen letters arriving partially from Hungary and partially from abroad. The changes experienced on the letters proved increasingly the suspect that an unauthorized person was in action between sender and receiver – probably for a content review of the letter.