> Uwe Brauer wrote:

> This

> Subject: An offer you can't refuse ...
>          ^

> is what happens I think? That's not what you want?

> I have this, what you ask for happens by default, but if point
> didn't change, the user meant something else so it moves to
> the beginning of the line instead, disregarding the
> `message-mode' and header context.

> (defun message-bol ()
>   (interactive)
>   (let ((beg (point))
>         (end (progn (message-beginning-of-line) (point))) )
>     (when (= beg end)
>       (forward-line 0) )))

Thanks, so I did 

(defun my-add-subject-test2 ()
  (interactive)
  (message-goto-subject)
  (message-bol)
  (insert "[Test]2 "))


(defun message-bol ()
  (interactive)
  (let ((beg (point))
        (end (progn (message-beginning-of-line) (point))) )
    (when (= beg end)
      (forward-line 0) )))


But this did not work for an empty subject line, while Eric's suggestion does. 😉