7.1.3 Dynamic Modification of Messages

You can set wl-draft-config-alist so that header and body of the message will automatically modified depending on information of header and others.

The initial setting of wl-draft-config-alist is nil.

In the example below, the header is modified when wl-draft-send-and-exit or wl-draft-send is invoked. You can set wl-interactive-send to non-nil so as to confirm changes before sending the message.

(setq wl-draft-config-alist
      '(((string-match "aaa\\.example\\.com$" (system-name))
         ;; applied if the expression is non-nil
         (wl-smtp-posting-server . "mailserver-B")
         (wl-nntp-posting-server . "newsserver-B")
         ;; settings of temporary variables
         )
        ("^To: .*user@aaa\\.bbb\\.example\\.com"
         ;; applied if it matches the header of the draft buffer
         ("Organization" . (format "Go %s" my-webpage)))
                       ;; you can write elisp expressions here (eval only)
         (top . "Hello.\n")    ;; inserted at the top of the body
         (bottom . "\nBye.\n") ;; inserted at the bottom of the body
        ))

The format of wl-draft-config-alist is:

'(("regexp of the header" or elisp expression
  ("Field" . value(elisp expression))
   (variable . value(elisp expression))
   (sub-function . value(elisp expression))
   function
   ...)
  ("regexp of the header" or elisp expression
   ("Field" . value(elisp expression))
   ...))

Per default, there are 13 following sub-functions.

'header:      Inserts the specified string at the bottom of the header.
'header-top:  Inserts the specified string at the top of the header.
'header-file: Inserts the specified file at the bottom of the header.
'x-face:      Inserts `X-Face:' field with the content of the specified file.
'top:         Inserts the specified string at the top of the body.
'top-file:    Inserts the specified file at the top of the body.
'body:        Replaces the body with the specified string.
              Specifying nil deletes the entire body string.
'body-file:   Replaces the body with the content of the specified file.
'bottom:      Inserts the specified string at the bottom of the body.
'bottom-file: Inserts the specified file at the top of the body.
'part-top:  Inserts the specified string at the top of the current part.
'part-bottom: Inserts the specified string at the bottom of the current part.
'template:    Applies the specified template.
              (refer to the next subsection)

These are defined in wl-draft-config-sub-func-alist and you can change them or add your own functions. If you read the code, you can easily find how to write the functions.

At the first of each item, a regular expression of the header or an elisp expression should be specified. In the case of an elisp expression, the item is applied when the expression is evaluated non-nil.

Per default, when multiple items match or are evaluated non-nil, all such items are applied, but if you set a variable wl-draft-config-matchone to t, only the first matching one is applied.

At the second of the item, a cons or a list of functions should be specified. The car part of the cons should be a header field, a variable, or a sub-function. When a header field is specified, the field will be modified. If a variable is specified, the value of the variable will be modified temporarily.

In the cdr part of a cons, not only a variable but also an elisp expression can be specified as is. If the car part is a header field and the cdr part is nil, the field will be deleted.

See the next example as well:

(setq wl-draft-config-alist
      '((reply                         ;; (1)
         "X-ML-Name: \\(Wanderlust\\|emacs-mime-ja\\|apel-ja\\)"
         ;; applied if it matches the header of the buffer being replied
         (body . "  Hello.\n")
         (template . "default")
         )))

As in the (1) above, if a header regexp is prepended with reply, it is applied when the draft is prepared by wl-summary-reply for example, and when it matches the header being replied. It is ignored when there is no buffer being replied, like after wl-draft was invoked.

If you want to use name of parent folder, you can refer the buffer local variable wl-draft-parent-folder. In the following example, Wanderlust changes From according to the folder name of the summary in which the draft was invoked.

(setq wl-draft-config-alist
      '(((string-match \".*@domain1$\" wl-draft-parent-folder)
         (\"From\" . \"user@domain1\"))
        ((string-match \".*@domain2$\" wl-draft-parent-folder)
         (\"From\" . \"user@domain2\"))))

Note that wl-draft-config-alist is applied only once when wl-draft-send-and-exit or wl-draft-send is invoked. Therefore, if you want to apply wl-draft-config-alist again after aborting transmission, execute C-c C-e (wl-draft-config-exec) explicitly.

If you don't want to apply wl-draft-config-alist when wl-draft-send-and-exit or wl-draft-send is invoked, do the following:

(remove-hook 'wl-draft-send-hook 'wl-draft-config-exec)

If you want to apply wl-draft-config-alist when a draft buffer is prepared, do the following:

(add-hook 'wl-mail-setup-hook 'wl-draft-config-exec)

If you want to apply wl-draft-config-alist when you re-edit a mail from summary mode by typing E(wl-summary-reedit), do the following:

(add-hook 'wl-draft-reedit-hook 'wl-draft-config-exec)