Newbie question defining deleted map

["Jürgen Beier" <jube100@gmx.de>]

Hi,

I am trying to set up notmuch-emacs.

I found the advice in the faq to define an key map "d" to add a "deleted 
tag" to the mail to be used in the notmuch message mode.

I put according to the advice the following in my .emacs file:


(define-key notmuch-show-mode-map "d"
     (lambda ()
       (interactive)
        (notmuch-show-tag "+deleted")))


and I get the following error:


Warning (initialization): An error occurred while loading 
`/home/beier/.emacs':

Symbol's value as variable is void: notmuch-show-mode-map

To ensure normal operation, you should investigate and remove the
cause of the error in your initialization file.  Start Emacs with
the `--debug-init' option to view a complete error backtrace.

Doing this I get the following:


Debugger entered--Lisp error: (void-variable notmuch-show-mode-map)
   (define-key notmuch-show-mode-map "d" (function (lambda nil 
(interactive) (notmuch-show-tag "+deleted"))))
   eval-buffer(#<buffer  *load*> nil "/home/beier/.emacs" nil t)  ; 
Reading at buffer position 17386
   load-with-code-conversion("/home/beier/.emacs" "/home/user/.emacs" t t)
   load("~/.emacs" t t)

[...]

[init-file-user system-type delayed-warnings-list user-init-file 
inhibit-default-init inhibit-startup-screen ms-dos "~" "/_emacs" 
windows-nt "/.emacs" directory-files nil "^\\.emacs\\(\\.elc?\\)?$" 
"~/.emacs" "^_emacs\\(\\.elc?\\)?$" (initialization "`_emacs' init file 
is deprecated, please use `.emacs'") "~/_emacs" t load expand-file-name 
"init" file-name-as-directory "/.emacs.d" file-name-extension "elc" 
file-name-sans-extension ".el" file-exists-p file-newer-than-file-p 
message "Warning: %s is newer than %s" sit-for 1 "default"] 7 "\n\n(fn)"]()
   command-line()
   normal-top-level()

I am using:

GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
  of 2017-09-20 on lcy01-07, modified by Debian

Could you give me some advice? Thank you.


Juergen