gnus from field auto completion

gnus-from-completion.el

(defvar my-smtp-list
  '(("aa@bb"       "AA BB")
    ("cc@dd"       "西西滴滴")
    ("ee@ff"       "EeFf"))
  "A list of smtp account.")

(defun my-complete-sender ()
  "Complete email sender, from `my-smtp-list'."
  (interactive)
  (let* ((lst (mapcar
               (lambda (x)
                 (with-temp-buffer
                   (let ((user-mail-address (car x))
                         (user-full-name    (cadr x)))
                     (mail-insert-from-field)
                     (goto-char (point-min))
                     (delete-char (length "From: "))
                     (end-of-line)
                     (delete-char 1)
                     (buffer-string))))
               my-smtp-list))
         (sender (ido-completing-read "sender: " lst))
         (epos (point))
         (bpos (save-excursion
                 (re-search-backward "\\(\\`\\|[\n:,]\\)[ \t]*")
                 (goto-char (match-end 0))
                 (point))))
    (delete-region bpos epos)
    (insert sender)))

(setq message-completion-alist
      `(("^\\(Reply-To\\|From\\|Mail-Followup-To\\|Mail-Copies-To\\):"
         . my-complete-sender) .
         ,message-completion-alist))