When a player sends a message from a company they have not unlocked, it does not create a notification for the recipient(s): it does not increase unread message count and does not create a ticker message. While this may be desirable in some cases, in other cases it has been an issue, for example when chatting with a player who has not logged into their company.
unowned-chat-message-fix.patch removes this behaviour completely.
unowned-chat-message-fix-only-private.patch removes this behaviour, but only for private messages - there will be a notification for messages from players not logged in only for private messages.
Ok, looking into it, it does not trigger a notification, if the recipent is locked too, I see, incorporated. I disabled also sending company messages from locked players in r11764.