[TxMt] Mail bundle font setting

I use the Mail.bundle for editing my posts to usenet groups, usenet posts seem to look a lot like mail.

If the message I am posting contains quoted text the display is terrible. However I change my font settings the quoted text only changes size, I don't seem to be able to change the font used. I can't find anything in the Mail bundle that relates to font to change this. My usual font (coding and posting to usenet) is Andale Mono Regular (with Antialiasing off), here's the abomination I'm faced with if there is quoted text in my message:

Any ideas where this is set, so that I can change it?