Just a little FYI about a little CWM - in most* cases, when sending a private message to somebody that is ignoring you, you'll be informed about their ignoring you. You can customize how you're informed at your user settings, under the "Private message filter" section.
* Yes, "most". Messages sent via chatterbox's /msg command do not yet give blocking information. If everything goes smoothly, the /msg will soon behave in the same fashion.
Please, please, if you encounter any strange behaviors with private messages, send N-Wing a message.