David Wen Riccardi-Zhu <dwrz@dwrz.net> writes:

> When I run a search with notmuch (on Emacs), olders email are shown first
> (at the top of the screen). This is inconvenient, since the majority of
> my searches relate to more recent emails. Is there a way to flip the
> output around, so that newer mails appear first?

Check out the variable notmuch-search-oldest-first. I have this set in
my notmuch-config:

   (setq notmuch-search-oldest-first t)

you should have

   (setq notmuch-search-oldest-first nil)

I guess. Also, in a notmuch-search buffer, the effect of pressing o for
me is to toggle the search order. C-h k o

   o runs the command notmuch-search-toggle-order, which is an
   interactive compiled Lisp function in `notmuch.el'.

   It is bound to o.

   (notmuch-search-toggle-order)

   Toggle the current search order.