So I was doing the White Rose Prison questline, and when it tells you to talk to General (name) after talking to a guard, I did, or tired to. I couldn't talk to him, hitting 'Talk' would not make him talk. I went outside of his area and tried to swing my weapon, I could not unsheathe it. Then I got booted, error message below, and in the title.
So excuse me? I didn't send ANY messages. In fact, I don't think I've EVER sent any message using the in-game Mail system. The only time I use Mail is when I get something from a hireling or a reward, but I don't compose outgoing mail.