When someone went into a prison or some sort of detainment place like that, they would not be able to send a message outside. Even for players, they could not send any message out from in-game.
When a player was captured, there were some restrictions on them. Their private message function would be disabled for a moment. They also could not delete their character until they were freed from the prison.
However, there was still a way for a player to spread the news outside. They could log out of the game and told their friends about the story. Then, their friends would log in to the game and spreads the news.
But, by doing this, there were some disadvantages. It would take some time for the news to spread. If your friend had a significant influence or position inside the game, then it would be easy for the NPC or other players to believe them.