The letters stated that I had a contractual obligation to assist. But I noticed at the top they were stamped 'without prejudice'. I asked my friend what that me

The letters stated that I had a contractual obligation to assist. But I noticed at the top they were stamped 'without prejudice'. I asked my friend what that meant, and he said that technically it's not a legal letter - so I ignored them. For a while, I made it game to light the various communications on fire in interesting ways, but it got boring.