🚀 go-pugleaf

wisner@mica.berkeley.edu writes:
   How do I get C-c C-y in news-reply mode to prefix yanked lines with angle
   brackets instead of three spaces?

I don't think you can unless you write your own mail-yank-original.

GNUS borrows heavily from rnewspost.el, which in turn borrows heavily
from sendmail.el.  About 4 function calls deep, C-c C-y turns into a
call to mail-yank-original in sendmail.el.  The ARG for this function
determines the number of spaces of indentation, default 3, and use of
just universal-argument causes it not to indent or strip any headers.
But there is no provision for a different "quoting character."

--Karl