Just a heads up on this because I only recently discovered it myself.
If you choose to 'Leave' a Conversation and select the option to 'Ignore future messages' then the other person/people in the Conversation will not know you have left. They can continue replying but you will not see the messages. It's designed this way to allow people to remove themselves silently.
If you want to restrict the people who can send you private messages then you can change the 'Start conversations with you' settings here: https://thefightingcock.co.uk/forum/account/privacy
If you choose to 'Leave' a Conversation and select the option to 'Ignore future messages' then the other person/people in the Conversation will not know you have left. They can continue replying but you will not see the messages. It's designed this way to allow people to remove themselves silently.
If you want to restrict the people who can send you private messages then you can change the 'Start conversations with you' settings here: https://thefightingcock.co.uk/forum/account/privacy