Julien Danjou <julien@danjou.info> writes:

> On Thu, Jul 26 2012, Greg Troxel wrote:
>
>>   message-get-reply-headers: Autoloading failed to define function
>> mail-dont-reply-to
>>
>> when typing 'r' to a message in nnimap summary.
>
> Hm, which Emacs version are you running?

GNU Emacs 23.3.1
Copyright (C) 2011 Free Software Foundation, Inc.
GNU Emacs comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of Emacs
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING.

on NetBSD 5.1_STABLE i386

I went back to ca6a7ca and now it works.