emacs-mime: Display Customization
1.5 Display Customization
=========================
‘mm-inline-media-tests’
This is an alist where the key is a MIME type, the second element
is a function to display the part “inline” (i.e., inside Emacs),
and the third element is a form to be ‘eval’ed to say whether the
part can be displayed inline.
This variable specifies whether a part _can_ be displayed inline,
and, if so, how to do it. It does not say whether parts are
_actually_ displayed inline.
‘mm-inlined-types’
This, on the other hand, says what types are to be displayed
inline, if they satisfy the conditions set by the variable above.
It’s a list of MIME media types.
‘mm-automatic-display’
This is a list of types that are to be displayed “automatically”,
but only if the above variable allows it. That is, only inlinable
parts can be displayed automatically.
‘mm-automatic-external-display’
This is a list of types that will be displayed automatically in an
external viewer.
‘mm-keep-viewer-alive-types’
This is a list of media types for which the external viewer will
not be killed when selecting a different article.
‘mm-attachment-override-types’
Some MIME agents create parts that have a content-disposition of
‘attachment’. This variable allows overriding that disposition and
displaying the part inline. (Note that the disposition is only
overridden if we are able to, and want to, display the part
inline.)
‘mm-discouraged-alternatives’
List of MIME types that are discouraged when viewing
‘multipart/alternative’. Viewing agents are supposed to view the
last possible part of a message, as that is supposed to be the
richest. However, users may prefer other types instead, and this
list says what types are most unwanted. If, for instance,
‘text/html’ parts are very unwanted, and ‘text/richtext’ parts are
somewhat unwanted, you could say something like:
(setq mm-discouraged-alternatives
'("text/html" "text/richtext")
mm-automatic-display
(remove "text/html" mm-automatic-display))
Adding ‘"image/.*"’ might also be useful. Spammers use images as
the preferred part of ‘multipart/alternative’ messages, so you
might not notice there are other parts. See also
‘gnus-buttonized-mime-types’, 
MIME Commands (gnus)MIME
Commands. After adding ‘"multipart/alternative"’ to
‘gnus-buttonized-mime-types’ you can choose manually which
alternative you’d like to view. For example, you can set those
variables like:
(setq gnus-buttonized-mime-types
'("multipart/alternative" "multipart/signed")
mm-discouraged-alternatives
'("text/html" "image/.*"))
In this case, Gnus will display radio buttons for such a kind of
spam message as follows:
1. (*) multipart/alternative ( ) image/gif
2. (*) text/plain ( ) text/html
‘mm-inline-large-images’
When displaying inline images that are larger than the window,
Emacs does not enable scrolling, which means that you cannot see
the whole image. To prevent this, the library tries to determine
the image size before displaying it inline, and if it doesn’t fit
the window, the library will display it externally (e.g., with
‘ImageMagick’ or ‘xv’). Setting this variable to ‘t’ disables this
check and makes the library display all inline images as inline,
regardless of their size. If you set this variable to ‘resize’,
the image will be displayed resized to fit in the window, if Emacs
has the ability to resize images.
‘mm-inline-large-images-proportion’
The proportion used when resizing large images.
‘mm-inline-override-types’
‘mm-inlined-types’ may include regular expressions, for example to
specify that all ‘text/.*’ parts be displayed inline. If a user
prefers to have a type that matches such a regular expression be
treated as an attachment, that can be accomplished by setting this
variable to a list containing that type. For example assuming
‘mm-inlined-types’ includes ‘text/.*’, then including ‘text/html’
in this variable will cause ‘text/html’ parts to be treated as
attachments.
‘mm-text-html-renderer’
This selects the function used to render HTML. The predefined
renderers are selected by the symbols ‘gnus-article-html’,
‘w3m’(1), ‘links’, ‘lynx’, ‘w3m-standalone’ or ‘html2text’. If
‘nil’ use an external viewer. You can also specify a function,
which will be called with a MIME handle as the argument.
‘mm-html-inhibit-images’
If this is non-‘nil’, inhibit displaying of images inline in the
article body. It is effective to images in HTML articles rendered
when ‘mm-text-html-renderer’ (Display Customization) is
‘shr’ or ‘w3m’. In Gnus, this is overridden by the value of
‘gnus-inhibit-images’ (Misc Article (gnus)Misc Article.).
The default is ‘nil’.
‘mm-html-blocked-images’
External images that have URLs that match this regexp won’t be
fetched and displayed. For instance, to block all URLs that have
the string “ads” in them, do the following:
(setq mm-html-blocked-images "ads")
It is effective when ‘mm-text-html-renderer’ (Display
Customization) is ‘shr’. In Gnus, this is overridden by the
value of ‘gnus-blocked-images’ or the return value of the function
that ‘gnus-blocked-images’ is set to (HTML (gnus)HTML.).
Some HTML mails might have the trick of spammers using ‘<img>’
tags. It is likely to be intended to verify whether you have read
the mail. You can prevent your personal information from leaking
by setting this option to ‘""’ (which is the default).
‘mm-w3m-safe-url-regexp’
A regular expression that matches safe URL names, i.e., URLs that
are unlikely to leak personal information when rendering HTML email
(the default value is ‘\\`cid:’). If ‘nil’ consider all URLs safe.
In Gnus, this will be overridden according to the value of the
variable ‘gnus-safe-html-newsgroups’, Various Various
(gnus)Various Various.
‘mm-inline-text-html-with-w3m-keymap’
You can use emacs-w3m command keys in the inlined text/html part by
setting this option to non-‘nil’. The default value is ‘t’.
‘mm-external-terminal-program’
The program used to start an external terminal.
‘mm-enable-external’
Indicate whether external MIME handlers should be used.
If ‘t’, all defined external MIME handlers are used. If ‘nil’,
files are saved to disk (‘mailcap-save-binary-file’). If it is the
symbol ‘ask’, you are prompted before the external MIME handler is
invoked.
When you launch an attachment through mailcap (mailcap) an
attempt is made to use a safe viewer with the safest options—this
isn’t the case if you save it to disk and launch it in a different
way (command line or double-clicking). Anyhow, if you want to be
sure not to launch any external programs, set this variable to
‘nil’ or ‘ask’.
---------- Footnotes ----------
(1) See <http://emacs-w3m.namazu.org/> for more information about
emacs-w3m
Info Catalog
emacs-mime: Display
emacs-mime: Decoding and Viewing
emacs-mime: Files and Directories