>>I define a "message-setup-hook" which for some reason has the unintended
>>side-effect of turning off undo in the result message-mode buffer
>>[buffer-undo-list has a value of t].
> 
> 
> Here's a simpler example of the same thing (?):

Thanks for noting.

> http://lists.gnu.org/archive/html/emacs-devel/2008-02/msg02302.html
> 
>   From:   Bill Wohler
>   Subject:     23.0.60; Disabled undo
>   Date:        Sat, 23 Feb 2008 22:07:26 -0800

Bill, please try whether the attached patch works.