Re: Rmail: rmail-enable-mime is causing troubles

[Henrik Enberg]

>    When setting rmail-enable-mime in my .emacs to t, I get a backtrace
>    when I try to display a message like this one:
> 
> I believe that `rmail-enable-mime' does not work unless you install
> some package (not included in Emacs by default) whose name I forgot,
> even though the docstring suggests that all you have to do is set it
> to t to make it work.  This has confused many people in the nine years
> since this variable was first introduced.
> 
> If you have no extra Emacs packages installed, set rmail-enable-mime
> to t and do `M-x rmail' you get:
> 
> Feature `rmail-mime' not provided
> 
> There is a lot of code in CVS Emacs related to `rmail-enable-mime', but
> I believe that this code is only meant to support the external package.
> Maybe somebody more familiar with the feature than I am can shed more
> light on this.

I've only ever seen one package that provides `rmail-mime'.  It seems to
be by the same people who wrote the `semi' library.  Unfortunately, I've
never been able to get it to work in CVS Emacs.

The popular choice for mime in RMAIL seem to be rmime.el by Ray Moody.
This package makes use of external programs for decoding, and probably
only works on unix-like systems.  It also reformats the source rmail
file instead of creating a temporary mime buffer, something I find
undesirable.

I once looked at writing mime support using the Gnus mime libraries, but
I was never really able to understand the hooks RMAIL provides for this
purpose.  They're quite sparse on documentation.