(I am using notmuch 0.22 from the Debian 0.22-1 package, in Emacs 24.5.1.) I start gnus-alias in my message-setup-hook: (add-hook 'message-setup-hook 'gnus-alias-determine-identity) That worked fine until recently. Now it fails with the following error (in the *Messages* buffer and minibuffer): apply: Must be in `message-mode'.? The problem is the following in gnus-alias.el: (defun gnus-alias-ensure-message-mode () "Assert that the current buffer is a message buffer." (when (not (eq major-mode 'message-mode)) (gnus-alias-error "Must be in `message-mode'.? "))) The latest notmuch-mua.el doesn't use message-mode directly but rather defines a derived mode: (define-derived-mode notmuch-message-mode message-mode "Message[Notmuch]" "Notmuch message composition mode. Mostly like `message-mode'" (when notmuch-address-command (notmuch-address-setup))) I'm not sure what the best fix is. But I've done the following, which works for me: (require 'gnus-alias) (gnus-alias-init) ;;; upstream version checks just for message-mode, but notmuch uses ;;; notmuch-message-mode, which is derived from message-mode (defun gnus-alias-ensure-message-mode () "Assert that the current buffer is a message buffer." (when (not (derived-mode-p 'notmuch-message-mode)) (gnus-alias-error "Must be in `message-mode' or mode derived from it. "))) (add-hook 'message-setup-hook 'gnus-alias-determine-identity) -- -Sanjoy <http://savelongwharfpark.org/> Save Long Wharf Park in Boston Harbor! <http://streetfightingmath.com/> Six reasoning tools to make hard problems easy.