Ian Kelling <ian@iankelling.org> writes:

> gnus-alias allows you to set your identity based on the headers in the
> message you are replying. This is an essential feature in a mail client
> for me, I want to automatically reply as the person an email was sent to
> for certain addresses. This does not work in notmuch.

Which version of notmuch are you using?  gnus-alias is working fine for
me with notmuch 0.17 and emacs-version "GNU Emacs 24.4.50.2
(x86_64-pc-linux-gnu, GTK+ Version 3.8.6) of 2014-04-04 on wani04"

Cheers,
mwh