I've made some assumptions based on what I tested:

It seems like mIRC encodes to unicode just before sending the message. Meaning that regardless of the command I use (/msg, /raw PRIVMSG and whatnot) if it encounters a "PRIVMSG #channel :" where #channel is set to utf8 encode (Display and Encode in fonts options), it encodes it. I can send the exact same message to "Msmo,#channel" and it won't be encoded, but not all servers allow a comma for multi-targetting.


Problem:

I need to send a message, not utf8 encoded, from a script to a channel which is set as Display and Encode in fonts options.


Feature suggestion:

A flag for /raw or a new command to prevent utf8 encoding.