Attachment weirdness

[Cameron Simpson]

On 13May2019 15:45, Patrick Shanahan <paka at opensuse.org> wrote:
>* jeremy bentham <dnw at eskimo.com> [05-13-19 15:41]:
>> I used xwd to take a screen dump, then imagemagick to trim and
>> save it as a gif.
>>
>> When I tried to attach it to a message, mutt decided it was
>> "audio/basic", as it did with a jpeg of the same image.
[...]
>iianm, mutt does not "decide" the file-type, mime does.  you need to
>adjust your mime settings.

In more detail:

This comes from the mime.types mapping, which is stored in 
/etc/mime.types with personal overrides/additons in ~/.mime.types. This 
is just a text file with an association of a MIME Content-Type to 
various file extensions. Example line:

  image/jpeg jpg jpeg jpe jfif pjpeg pjp

Cheers,
Cameron Simpson <cs at cskk.id.au>