Oddly this more resembles the irc /notice command more than anything else and actually their implementation prevents us from thinking it is anything like a user-to-user private msg and makes us devs follow irc protocol.
The NOTICE command is used similarly to PRIVMSG. The difference between NOTICE and PRIVMSG is that automatic replies MUST NEVER be sent in response to a NOTICE message. This rule applies to servers REF RFC2812 https://tools.ietf.org/html/rfc2812#section-3.3.2