>>>>> In <877iug6szc.fsf@catnip.gol.com> Miles Bader wrote:

> Katsumi Yamaoka <yamaoka@jpl.org> writes:
>> By default, Gnus uses the "inline" disposition for an attachment of
>> which the MIME type is text/* except text/rtf[1].  So, the reason
>> seems to be that the text/* MIME type is specified in your system
>> for *.csv files.  You know how to customize it already. ;-)

> Actually I've always thought that this behavior of Gnus was sort of dumb
> -- I don't think it really makes sense to inline random text/ sub-types.
> Glancing through the list of text/ sub-types in /etc/mime.types, most
> look like the sort of thing I wouldn't want inline; in practice I also
> find that I usually have to override the default (the one which annoys
> most often is text/x-diff).

> Instead I think Gnus should default to "attach", and have a list of
> text/ sub-types which _should_ be inlined (bonus for making it a real
> configurable list, not hardwired in the code...).

I made such one for a trial.  Is this worth implementing in Gnus?

--8<---------------cut here---------------start------------->8---
mml-content-disposition-alist is a variable defined in `mml.el'.
Its value is 
((text
  (rtf . "attachment")
  (t . "inline"))
 (t . "attachment"))

Documentation:
Alist of MIME types or regexps matching file names and default dispositions.
Each element should be one of the following three forms:

  (REGEXP . DISPOSITION)
  (TYPE (SUBTYPE . DISPOSITION) (SUBTYPE . DISPOSITION)...)
  (TYPE . DISPOSITION)

Where REGEXP is a string which matches the file name (if any) of an
attachment, TYPE is a MIME type and SUBTYPE is a MIME subtype of an
attachment, and DISPOSITION should be either "attachment" or "inline".
The value t for TYPE or SUBTYPE matches any MIME types or MIME
subtypes.  The first match found will be used.
--8<---------------cut here---------------end--------------->8---

I did set the default value so as not to change the present
behavior of Gnus.  For instance, Sebastian may want to use the
following:

--8<---------------cut here---------------start------------->8---
(add-to-list 'mml-content-disposition-alist
	     '("\\.csv\\'" . "attachment"))
--8<---------------cut here---------------end--------------->8---

Here's a patch to the Gnus CVS trunk: