This section describes how Rmail displays mail headers, MIME sections and attachments, URLs, and encrypted messages.
Before displaying each message for the first time, Rmail reformats
its header, hiding uninteresting header fields to reduce clutter. The
rmail-toggle-header) command toggles this, switching
between showing the reformatted header fields and showing the
complete, original header. With a positive prefix argument, the
command shows the reformatted header; with a zero or negative prefix
argument, it shows the full header. Selecting the message again also
reformats it if necessary.
rmail-ignored-headers holds a regular expression
specifying the header fields to hide; any matching header line will be
hidden. The variable
rmail-nonignored-headers overrides this:
any header field matching that regular expression is shown even if it
rmail-ignored-headers too. The variable
rmail-displayed-headers is an alternative to these two
variables; if non-
nil, this should be a regular expression
specifying which headers to display (the default is
Rmail highlights certain header fields that are especially
interesting—by default, the ‘From’ and ‘Subject’ fields.
This highlighting uses the
rmail-highlight face. The variable
rmail-highlighted-headers holds a regular expression specifying
the header fields to highlight; if it matches the beginning of a
header field, that whole field is highlighted. To disable this
If a message is in MIME (Multipurpose Internet Mail Extensions) format and contains multiple parts (MIME entities), Rmail displays each part with a tagline. The tagline summarizes the part's index, size, and content type. Depending on the content type, it may also contain one or more buttons; these perform actions such as saving the part into a file.
Each plain-text MIME part is initially displayed immediately after its tagline, as part of the Rmail buffer, while MIME parts of other types are represented only by their taglines, with their actual contents hidden. In either case, you can toggle a MIME part between its displayed and hidden states by typing <RET> anywhere in the part—or anywhere in its tagline (except for buttons for other actions, if there are any). Type <RET> (or click with the mouse) to activate a tagline button, and <TAB> to cycle point between tagline buttons.
The v (
rmail-mime) command toggles between the default
MIME display described above, and a raw display showing
the undecoded MIME data. With a prefix argument, this
command toggles the display of only an entity at point.
If the message has an HTML MIME part, Rmail
displays it in preference to the plain-text part, if Emacs can render
HTML1. To prevent
that, and have the plain-text part displayed instead, customize the
rmail-mime-prefer-html to a
To prevent Rmail from handling MIME decoded messages, change the
nil. When this is the
case, the v (
rmail-mime) command instead creates a
temporary buffer to display the current MIME message.
If the current message is an encrypted one, use the command M-x rmail-epa-decrypt to decrypt it, using the EasyPG library (see EasyPG).
You can highlight and activate URLs in the Rmail buffer using Goto Address mode:
(add-hook 'rmail-show-message-hook 'goto-address-mode)
Then you can browse these URLs by clicking on them with mouse-2 (or mouse-1 quickly) or by moving to one and typing C-c <RET>. See Activating URLs.
 This capability requires that Emacs be built with libxml2 support or that you have the Lynx browser installed.