The /msg command and the /notice command both directly interface to the IRC server, and does not perform actual message handling. The audience that sees your messages is determined by the target you specified, and ultimately, any wacky designs of the irc network you are on.
Usage: /msg Target Message goes here.
Does: PRIVMSG Target :Message goes here.
Usage: /notice Target Message goes here.
Does: NOTICE Target :Message goes here.
Nothing about this simple construct has changed in any version of mIRC.
