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# Reading Mail with Rmail

Rmail is an Emacs subsystem for reading and disposing of mail that you receive. Rmail stores mail messages in files called Rmail files. Reading the message in an Rmail file is done in a special major mode, Rmail mode, which redefines most letters to run commands for managing mail.

- Basic: Basic concepts of Rmail, and simple use.
- Scroll: Scrolling through a message.
- Motion: Moving to another message.
- Deletion: Deleting and expunging messages.
- Inbox: How mail gets into the Rmail file.
- Files: Using multiple Rmail files.
- Output: Copying message out to files.
- Labels: Classifying messages by labeling them.
- Reply: Sending replies to messages you are viewing.
- Summary: Summaries show brief info on many messages.
- Sort: Sorting messages in Rmail.
- Display: How Rmail displays a message; customization.
- Editing: Editing message text and headers in Rmail.
- Digest: Extracting the messages from a digest message.
- Out of Rmail: Converting an Rmail file to mailbox format.
- Rot13: Reading messages encoded in the rot13 code.

## Basic Concepts of Rmail

Using Rmail in the simplest fashion, you have one Rmail file ``~/RMAIL'` in which all of your mail is saved. It is called your primary Rmail file. The command `M-x rmail` reads your primary Rmail file, merges new mail in from your inboxes, displays the first message you haven't read yet, and lets you begin reading. The variable `rmail-file-name` specifies the name of the primary Rmail file.

Rmail uses narrowing to hide all but one message in the Rmail file. The message that is shown is called the current message. Rmail mode's special commands can do such things as delete the current message, copy it into another file, send a reply, or move to another message. You can also create multiple Rmail files and use Rmail to move messages between them.

Within the Rmail file, messages are normally arranged sequentially in order of receipt; you can specify other ways to sort them. Messages are assigned consecutive integers as their message numbers. The number of the current message is displayed in Rmail's mode line, followed by the total number of messages in the file. You can move to a message by specifying its message number with the `j` key (see section Moving Among Messages).

Following the usual conventions of Emacs, changes in an Rmail file become permanent only when the file is saved. You can save it with `s` (`rmail-save`), which also expunges deleted messages from the file first (see section Deleting Messages). To save the file without expunging, use `C-x C-s`. Rmail also saves the Rmail file after merging new mail from an inbox file (see section Rmail Files and Inboxes).

You can exit Rmail with `q` (`rmail-quit`); this expunges and saves the Rmail file and then switches to another buffer. But there is no need to `exit' formally. If you switch from Rmail to editing in other buffers, and never happen to switch back, you have exited. (The Rmail command `b`, `rmail-bury`, does this for you.) Just make sure to save the Rmail file eventually (like any other file you have changed). `C-x s` is a good enough way to do this (see section Saving Files).

## Scrolling Within a Message

When Rmail displays a message that does not fit on the screen, you must scroll through it to read the rest. You could do this with `C-v`, `M-v` and `M-<`, but in Rmail scrolling is so frequent that it deserves to be easier to type.

``SPC``
  Scroll forward (`scroll-up`).
``DEL``
  Scroll backward (`scroll-down`).
`.`
  Scroll to start of message (`rmail-beginning-of-message`).

Since the most common thing to do while reading a message is to scroll through it by screenfuls, Rmail makes `SPC` and `DEL` synonyms of `C-v` (`scroll-up`) and `M-v` (`scroll-down`)

The command `.` (`rmail-beginning-of-message`) scrolls back to the beginning of the selected message. This is not quite the same as `M-<`: for one thing, it does not set the mark; for another, it resets the buffer boundaries to the current message if you have changed them.

## Moving Among Messages

The most basic thing to do with a message is to read it. The way to do this in Rmail is to make the message current. The usual practice is to move sequentially through the file, since this is the order of receipt of messages. When you enter Rmail, you are positioned at the first message that you have not yet made current (that is, the first one that has the ``unseen'` attribute; see section Labels). Move forward to see the other new messages; move backward to reexamine old messages.

`n`
  Move to the next nondeleted message, skipping any intervening deleted messages (`rmail-next-undeleted-message`).
`p`
  Move to the previous nondeleted message (`rmail-previous-undeleted-message`).
`M-n`
  Move to the next message, including deleted messages (`rmail-next-message`).
`M-p`
  Move to the previous message, including deleted messages (`rmail-previous-message`).
`j`
  Move to the first message. With argument n, move to message number n (`rmail-show-message`).
`>`
  Move to the last message (`rmail-last-message`).
`<`
  Move to the first message (`rmail-first-message`).
`M-s regexp `RET``
  Move to the next message containing a match for regexp (`rmail-search`).
`- M-s regexp `RET``
  Move to the previous message containing a match for regexp.

`n` and `p` are the usual way of moving among messages in Rmail. They move through the messages sequentially, but skip over deleted messages, which is usually what you want to do. Their command definitions are named `rmail-next-undeleted-message` and `rmail-previous-undeleted-message`. If you do not want to skip deleted messages--for example, if you want to move to a message to undelete it--use the variants `M-n` and `M-p` (`rmail-next-message` and `rmail-previous-message`). A numeric argument to any of these commands serves as a repeat count.

In Rmail, you can specify a numeric argument by typing just the digits. You don't need to type `C-u` first.

The `M-s` (`rmail-search`) command is Rmail's version of search. The usual incremental search command `C-s` works in Rmail, but it searches only within the current message. The purpose of `M-s` is to search for another message. It reads a regular expression (see section Syntax of Regular Expressions) nonincrementally, then searches starting at the beginning of the following message for a match. It then selects that message. If regexp is empty, `M-s` reuses the regexp used the previous time.

To search backward in the file for another message, give `M-s` a negative argument. In Rmail you can do this with `- M-s`.

It is also possible to search for a message based on labels. See section Labels.

To move to a message specified by absolute message number, use `j` (`rmail-show-message`) with the message number as argument. With no argument, `j` selects the first message. `<` (`rmail-first-message`) also selects the first message. `>` (`rmail-last-message`) selects the last message.

## Deleting Messages

When you no longer need to keep a message, you can delete it. This flags it as ignorable, and some Rmail commands pretend it is no longer present; but it still has its place in the Rmail file, and still has its message number.

Expunging the Rmail file actually removes the deleted messages. The remaining messages are renumbered consecutively. Expunging is the only action that changes the message number of any message, except for undigestifying (see section Digest Messages).

`d`
  Delete the current message, and move to the next nondeleted message (`rmail-delete-forward`).
`C-d`
  Delete the current message, and move to the previous nondeleted message (`rmail-delete-backward`).
`u`
  Undelete the current message, or move back to a deleted message and undelete it (`rmail-undelete-previous-message`).
`x`
  Expunge the Rmail file (`rmail-expunge`).

There are two Rmail commands for deleting messages. Both delete the current message and select another message. `d` (`rmail-delete-forward`) moves to the following message, skipping messages already deleted, while `C-d` (`rmail-delete-backward`) moves to the previous nondeleted message. If there is no nondeleted message to move to in the specified direction, the message that was just deleted remains current.

Whenever Rmail deletes a message, it invokes the function(s) listed in `rmail-delete-message-hook`. When the hook functions are invoked, the message has been marked deleted, but it is still the current message in the Rmail buffer.

To make all the deleted messages finally vanish from the Rmail file, type `x` (`rmail-expunge`). Until you do this, you can still undelete the deleted messages. The undeletion command, `u` (`rmail-undelete-previous-message`), is designed to cancel the effect of a `d` command in most cases. It undeletes the current message if the current message is deleted. Otherwise it moves backward to previous messages until a deleted message is found, and undeletes that message.

You can usually undo a `d` with a `u` because the `u` moves back to and undeletes the message that the `d` deleted. But this does not work when the `d` skips a few already-deleted messages that follow the message being deleted; then the `u` command undeletes the last of the messages that were skipped. There is no clean way to avoid this problem. However, by repeating the `u` command, you can eventually get back to the message that you intend to undelete. You can also select a particular deleted message with the `M-p` command, then type `u` to undelete it.

A deleted message has the ``deleted'` attribute, and as a result ``deleted'` appears in the mode line when the current message is deleted. In fact, deleting or undeleting a message is nothing more than adding or removing this attribute. See section Labels.

## Rmail Files and Inboxes

The operating system places incoming mail for you in a file that we call your inbox. When you start up Rmail, it runs a C program called `movemail` to copy the new messages from your inbox into your primary Rmail file, which also contains other messages saved from previous Rmail sessions. It is in this file that you actually read the mail with Rmail. This operation is called getting new mail. You can get new mail at any time in Rmail by typing `g`.

The variable `rmail-primary-inbox-list` contains a list of the files which are inboxes for your primary Rmail file. If you don't set this variable explicitly, it is initialized from the `MAIL` environment variable, or, as a last resort, set to `nil`, which means to use the default inbox. The default inbox is ``/var/mail/username'`, ``/usr/spool/mail/username'`, or ``/usr/mail/username'`, depending on your operating system. You can specify the inbox file(s) for any Rmail file with the command `set-rmail-inbox-list`; see section Multiple Rmail Files.

Some sites use a method called POP for accessing users' inbox data instead of storing the data in inbox files. `movemail` can work with POP if you compile it with the macro `MAIL_USE_POP` defined, and then install it setuid to `root`. It is safe to install `movemail` in this way. Note: `movemail` only works with POP3, not with older versions of POP.

Assuming you have compiled and installed `movemail` appropriately, you can specify a POP inbox with a "file name" of the form ``po:username'`. `movemail` handles such a name by opening a connection to the POP server. The `MAILHOST` environment variable specifies the machine to look for the server on.

Accessing mail via POP may require a password. If the variable `rmail-pop-password` is non-`nil`, it specifies the password to use for POP. Alternatively, if `rmail-pop-password-required` is non-`nil`, then Rmail asks you for the password to use.

There are two reasons for having separate Rmail files and inboxes.

1. The inbox file format varies between operating systems and according to the other mail software in use. Only one part of Rmail needs to know about the alternatives, and it need only understand how to convert all of them to Rmail's own format.
2. It is very cumbersome to access an inbox file without danger of losing mail, because it is necessary to interlock with mail delivery. Moreover, different operating systems use different interlocking techniques. The strategy of moving mail out of the inbox once and for all into a separate Rmail file avoids the need for interlocking in all the rest of Rmail, since only Rmail operates on the Rmail file.

Rmail was written to use Babyl format as its internal format. Since then, we have recognized that the usual inbox format on Unix and GNU systems is adequate for the job, and we plan to change Rmail to use that as its internal format. However, the Rmail file will still be separate from the inbox file, even on systems where their format is the same.

When getting new mail, Rmail first copies the new mail from the inbox file to the Rmail file; then it saves the Rmail file; then it truncates the inbox file. This way, a system crash may cause duplication of mail between the inbox and the Rmail file, but cannot lose mail.

When `movemail` copies mail from an inbox in the system's mailer directory, it actually puts it in an intermediate file ``~/.newmail-inboxname'`. Once it finishes, Rmail reads that file, merges the new mail, saves the Rmail file, and only then deletes the intermediate file. If there is a crash at the wrong time, this file continues to exist and Rmail will use it again the next time it gets new mail from that inbox.

## Multiple Rmail Files

Rmail operates by default on your primary Rmail file, which is named ``~/RMAIL'` and receives your incoming mail from your system inbox file. But you can also have other Rmail files and edit them with Rmail. These files can receive mail through their own inboxes, or you can move messages into them with explicit Rmail commands (see section Copying Messages Out to Files).

`i file `RET``
  Read file into Emacs and run Rmail on it (`rmail-input`).
`M-x set-rmail-inbox-list `RET` files `RET``
  Specify inbox file names for current Rmail file to get mail from.
`g`
  Merge new mail from current Rmail file's inboxes (`rmail-get-new-mail`).
`C-u g file `RET``
  Merge new mail from inbox file file.

To run Rmail on a file other than your primary Rmail file, you may use the `i` (`rmail-input`) command in Rmail. This visits the file in Rmail mode. You can use `M-x rmail-input` even when not in Rmail.

The file you read with `i` should normally be a valid Rmail file. If it is not, Rmail tries to decompose it into a stream of messages in various known formats. If it succeeds, it converts the whole file to an Rmail file. If you specify a file name that doesn't exist, `i` initializes a new buffer for creating a new Rmail file.

You can also select an Rmail file from a menu. Choose first the menu bar Classify item, then from the Classify menu choose the Input Rmail File item; then choose the Rmail file you want. The variables `rmail-secondary-file-directory` and `rmail-secondary-file-regexp` specify which files to offer in the menu: the first variable says which directory to find them in; the second says which files in that directory to offer (all those that match the regular expression). These variables also apply to choosing a file for output (see section Copying Messages Out to Files).

Each Rmail file can contain a list of inbox file names; you can specify this list with `M-x set-rmail-inbox-list `RET` files `RET``. The argument can contain any number of file names, separated by commas. It can also be empty, which specifies that this file should have no inboxes. Once a list of inboxes is specified, the Rmail file remembers it permanently until you specify a different list.

As a special exception, if your primary Rmail file does not specify any inbox files, it uses your standard system inbox.

The `g` command (`rmail-get-new-mail`) merges mail into the current Rmail file from its specified inboxes. If the Rmail file has no inboxes, `g` does nothing. The command `M-x rmail` also merges new mail into your primary Rmail file.

To merge mail from a file that is not the usual inbox, give the `g` key a numeric argument, as in `C-u g`. Then it reads a file name and merges mail from that file. The inbox file is not deleted or changed in any way when `g` with an argument is used. This is, therefore, a general way of merging one file of messages into another.

## Copying Messages Out to Files

These commands copy messages from an Rmail file into another file.

`o file `RET``
  Append a copy of the current message to the file file, using Rmail file format by default (`rmail-output-to-rmail-file`).
`C-o file `RET``
  Append a copy of the current message to the file file, using system inbox file format by default (`rmail-output`).

The commands `o` and `C-o` copy the current message into a specified file. This file may be an Rmail file or it may be in system inbox format; the output commands ascertain the file's format and write the copied message in that format.

The `o` and `C-o` commands differ in two ways: each has its own separate default file name, and each specifies a choice of format to use when the file does not already exist. The `o` command uses Rmail format when it creates a new file, while `C-o` uses system inbox format for a new file. The default file name for `o` is the file name used last with `o`, and the default file name for `C-o` is the file name used last with `C-o`.

If the output file is an Rmail file currently visited in an Emacs buffer, the output commands copy the message into that buffer. It is up to you to save the buffer eventually in its file.

You can also output a message to an Rmail file chosen with a menu. Choose first the menu bar Classify item, then from the Classify menu choose the Output Rmail Menu item; then choose the Rmail file you want. This outputs the current message to that file, like the `o` command. The variables `rmail-secondary-file-directory` and `rmail-secondary-file-regexp` specify which files to offer in the menu: the first variable says which directory to find them in; the second says which files in that directory to offer (all those that match the regular expression).

Copying a message gives the original copy of the message the ``filed'` attribute, so that ``filed'` appears in the mode line when such a message is current. If you like to keep just a single copy of every mail message, set the variable `rmail-delete-after-output` to `t`; then the `o` and `C-o` commands delete the original message after copying it. (You can undelete the original afterward if you wish.)

Copying messages into files in system inbox format uses the header fields that are displayed in Rmail at the time. Thus, if you use the `t` command to view the entire header and then copy the message, the entire header is copied. See section Display of Messages.

The variable `rmail-output-file-alist` lets you specify intelligent defaults for the output file, based on the contents of the current message. The value should be a list whose elements have this form:

    (regexp . name-exp)

If there's a match for regexp in the current message, then the default file name for output is name-exp. If multiple elements match the message, the first matching element decides the default file name. The subexpression name-exp may be a string constant giving the file name to use, or more generally it may be any Lisp expression that returns a file name as a string. `rmail-output-file-alist` applies to both `o` and `C-o`.

## Labels

Each message can have various labels assigned to it as a means of classification. Each label has a name; different names are different labels. Any given label is either present or absent on a particular message. A few label names have standard meanings and are given to messages automatically by Rmail when appropriate; these special labels are called attributes. All other labels are assigned only by users.

`a label `RET``
  Assign the label label to the current message (`rmail-add-label`).
`k label `RET``
  Remove the label label from the current message (`rmail-kill-label`).
`C-M-n labels `RET``
  Move to the next message that has one of the labels labels (`rmail-next-labeled-message`).
`C-M-p labels `RET``
  Move to the previous message that has one of the labels labels (`rmail-previous-labeled-message`).
`C-M-l labels `RET``
  Make a summary of all messages containing any of the labels labels (`rmail-summary-by-labels`).

The `a` (`rmail-add-label`) and `k` (`rmail-kill-label`) commands allow you to assign or remove any label on the current message. If the label argument is empty, it means to assign or remove the same label most recently assigned or removed.

Once you have given messages labels to classify them as you wish, there are two ways to use the labels: in moving and in summaries.

The command `C-M-n labels `RET`` (`rmail-next-labeled-message`) moves to the next message that has one of the labels labels. The argument labels specifies one or more label names, separated by commas. `C-M-p` (`rmail-previous-labeled-message`) is similar, but moves backwards to previous messages. A numeric argument to either command serves as a repeat count.

The command `C-M-l labels `RET`` (`rmail-summary-by-labels`) displays a summary containing only the messages that have at least one of a specified set of labels. The argument labels is one or more label names, separated by commas. See section Summaries, for information on summaries.

If the labels argument to `C-M-n`, `C-M-p` or `C-M-l` is empty, it means to use the last set of labels specified for any of these commands.

Some labels such as ``deleted'` and ``filed'` have built-in meanings and are assigned to or removed from messages automatically at appropriate times; these labels are called attributes. Here is a list of Rmail attributes:

``unseen'`
  Means the message has never been current. Assigned to messages when they come from an inbox file, and removed when a message is made current. When you start Rmail, it initially shows the first message that has this attribute.
``deleted'`
  Means the message is deleted. Assigned by deletion commands and removed by undeletion commands (see section Deleting Messages).
``filed'`
  Means the message has been copied to some other file. Assigned by the file output commands (see section Multiple Rmail Files).
``answered'`
  Means you have mailed an answer to the message. Assigned by the `r` command (`rmail-reply`). See section Sending Replies.
``forwarded'`
  Means you have forwarded the message. Assigned by the `f` command (`rmail-forward`). See section Sending Replies.
``edited'`
  Means you have edited the text of the message within Rmail. See section Editing Within a Message.
``resent'`
  Means you have resent the message. Assigned by the command `M-x rmail-resend`. See section Sending Replies.

All other labels are assigned or removed only by the user, and have no standard meaning.

## Sending Replies

Rmail has several commands that use Mail mode to send outgoing mail. See section Sending Mail, for information on using Mail mode. What are documented here are the special commands of Rmail for entering Mail mode. Note that the usual keys for sending mail---`C-x m`, `C-x 4 m`, and `C-x 5 m`---are available in Rmail mode and work just as they usually do.

`m`
  Send a message (`rmail-mail`).
`c`
  Continue editing already started outgoing message (`rmail-continue`).
`r`
  Send a reply to the current Rmail message (`rmail-reply`).
`f`
  Forward current message to other users (`rmail-forward`).
`C-u f`
  Resend the current message to other users (`rmail-resend`).
`M-m`
  Try sending a bounced message a second time (`rmail-retry-failure`).

The most common reason to send a message while in Rmail is to reply to the message you are reading. To do this, type `r` (`rmail-reply`). This displays the ``*mail*'` buffer in another window, much like `C-x 4 m`, but preinitializes the ``Subject'`, ``To'`, ``CC'` and ``In-reply-to'` header fields based on the message you are replying to. The ``To'` field starts out as the address of the person who sent the message you received, and the ``CC'` field starts out with all the other recipients of that message.

You can exclude certain recipients from being placed automatically in the ``CC'`, using the variable `rmail-dont-reply-to-names`. Its value should be a regular expression (as a string); any recipient that the regular expression matches, is excluded from the ``CC'` field. The default value matches your own name, and any name starting with ``info-'`. (Those names are excluded because there is a convention of using them for large mailing lists to broadcast announcements.)

To omit the ``CC'` field completely for a particular reply, enter the reply command with a numeric argument: `C-u r` or `1 r`.

Once the ``*mail*'` buffer has been initialized, editing and sending the mail goes as usual (see section Sending Mail). You can edit the presupplied header fields if they are not right for you. You can also use the commands of Mail mode (see section Mail Mode), including `C-c C-y` which yanks in the message that you are replying to. You can switch to the Rmail buffer, select a different message there, switch back, and yank the new current message.

Sometimes a message does not reach its destination. Mailers usually send the failed message back to you, enclosed in a failure message. The Rmail command `M-m` (`rmail-retry-failure`) prepares to send the same message a second time: it sets up a ``*mail*'` buffer with the same text and header fields as before. If you type `C-c C-c` right away, you send the message again exactly the same as the first time. Alternatively, you can edit the text or headers and then send it. The variable `rmail-retry-ignored-headers`, in the same format as `rmail-ignored-headers` (see section Display of Messages), controls which headers are stripped from the failed message when retrying it; it defaults to nil.

Another frequent reason to send mail in Rmail is to forward the current message to other users. `f` (`rmail-forward`) makes this easy by preinitializing the ``*mail*'` buffer with the current message as the text, and a subject designating a forwarded message. All you have to do is fill in the recipients and send. When you forward a message, recipients get a message which is "from" you, and which has the original message in its contents.

Forwarding a message encloses it between two delimiter lines. It also modifies every line that starts with a dash, by inserting ``- '` at the start of the line. When you receive a forwarded message, if it contains something besides ordinary text--for example, program source code--you might find it useful to undo that transformation. You can do this by selecting the forwarded message and typing `M-x unforward-rmail-message`. This command extracts the original forwarded message, deleting the inserted ``- '` strings, and inserts it into the Rmail file as a separate message immediately following the current one.

Resending is an alternative similar to forwarding; the difference is that resending sends a message that is "from" the original sender, just as it reached you--with a few added header fields ``Resent-from'` and ``Resent-to'` to indicate that it came via you. To resend a message in Rmail, use `C-u f`. (`f` runs `rmail-forward`, which is programmed to invoke `rmail-resend` if you provide a numeric argument.)

The `m` (`rmail-mail`) command is used to start editing an outgoing message that is not a reply. It leaves the header fields empty. Its only difference from `C-x 4 m` is that it makes the Rmail buffer accessible for `C-c C-y`, just as `r` does. Thus, `m` can be used to reply to or forward a message; it can do anything `r` or `f` can do.

The `c` (`rmail-continue`) command resumes editing the ``*mail*'` buffer, to finish editing an outgoing message you were already composing, or to alter a message you have sent.

If you set the variable `rmail-mail-new-frame` to a non-`nil` value, then all the Rmail commands to start sending a message create a new frame to edit it in. This frame is deleted when you send the message, or when you use the ``Don't Send'` item in the ``Mail'` menu.

## Summaries

A summary is a buffer containing one line per message to give you an overview of the mail in an Rmail file. Each line shows the message number, the sender, the labels, and the subject. Almost all Rmail commands are valid in the summary buffer also; these apply to the message described by the current line of the summary. Moving point in the summary buffer selects messages as you move to their summary lines.

A summary buffer applies to a single Rmail file only; if you are editing multiple Rmail files, each one can have its own summary buffer. The summary buffer name is made by appending ``-summary'` to the Rmail buffer's name. Normally only one summary buffer is displayed at a time.

- Rmail Make Summary: Making various sorts of summaries.
- Rmail Summary Edit: Manipulating messages from the summary.

### Making Summaries

Here are the commands to create a summary for the current Rmail file. Once the Rmail file has a summary buffer, changes in the Rmail file (such as deleting or expunging messages, and getting new mail) automatically update the summary.

`h`
`C-M-h`
  Summarize all messages (`rmail-summary`).
`l labels `RET``
`C-M-l labels `RET``
  Summarize message that have one or more of the specified labels (`rmail-summary-by-labels`).
`C-M-r rcpts `RET``
  Summarize messages that have one or more of the specified recipients (`rmail-summary-by-recipients`).
`C-M-t topic `RET``
  Summarize messages that have a match for the specified regexp topic in their subjects (`rmail-summary-by-topic`).

The `h` or `C-M-h` (`rmail-summary`) command fills the summary buffer for the current Rmail file with a summary of all the messages in the file. It then displays and selects the summary buffer in another window.

`C-M-l labels `RET`` (`rmail-summary-by-labels`) makes a partial summary mentioning only the messages that have one or more of the labels labels. labels should contain label names separated by commas.

`C-M-r rcpts `RET`` (`rmail-summary-by-recipients`) makes a partial summary mentioning only the messages that have one or more of the recipients rcpts. rcpts should contain mailing addresses separated by commas.

`C-M-t topic `RET`` (`rmail-summary-by-topic`) makes a partial summary mentioning only the messages whose subjects have a match for the regular expression topic.

Note that there is only one summary buffer for any Rmail file; making one kind of summary discards any previously made summary.

The variable `rmail-summary-window-size` says how many lines to use for the summary window.

### Editing in Summaries

You can use the Rmail summary buffer to do almost anything you can do in the Rmail buffer itself. In fact, once you have a summary buffer, there's no need to switch back to the Rmail buffer.

You can select and display various messages in the Rmail buffer, from the summary buffer, just by moving point in the summary buffer to different lines. It doesn't matter what Emacs command you use to move point; whichever line point is on at the end of the command, that message is selected in the Rmail buffer.

Almost all Rmail commands work in the summary buffer as well as in the Rmail buffer. Thus, `d` in the summary buffer deletes the current message, `u` undeletes, and `x` expunges. `o` and `C-o` output the current message to a file; `r` starts a reply to it. You can scroll the current message while remaining in the summary buffer using `SPC` and `DEL`.

The Rmail commands to move between messages also work in the summary buffer, but with a twist: they move through the set of messages included in the summary. They also ensure the Rmail buffer appears on the screen (unlike cursor motion commands, which update the contents of the Rmail buffer but don't display it in a window unless it already appears). Here is a list of these commands:

`n`
  Move to next line, skipping lines saying `deleted', and select its message.
`p`
  Move to previous line, skipping lines saying `deleted', and select its message.
`M-n`
  Move to next line and select its message.
`M-p`
  Move to previous line and select its message.
`>`
  Move to the last line, and select its message.
`<`
  Move to the first line, and select its message.
`M-s pattern `RET``
  Search through messages for pattern starting with the current message; select the message found, and move point in the summary buffer to that message's line.

Deletion, undeletion, and getting new mail, and even selection of a different message all update the summary buffer when you do them in the Rmail buffer. If the variable `rmail-redisplay-summary` is non-`nil`, these actions also bring the summary buffer back onto the screen.

When you are finished using the summary, type `w` (`rmail-summary-wipe`) to delete the summary buffer's window. You can also exit Rmail while in the summary: `q` (`rmail-summary-quit`) deletes the summary window, then exits from Rmail by saving the Rmail file and switching to another buffer.

## Sorting the Rmail File

`M-x rmail-sort-by-date`
  Sort messages of current Rmail file by date.
`M-x rmail-sort-by-subject`
  Sort messages of current Rmail file by subject.
`M-x rmail-sort-by-author`
  Sort messages of current Rmail file by author's name.
`M-x rmail-sort-by-recipient`
  Sort messages of current Rmail file by recipient's names.
`M-x rmail-sort-by-correspondent`
  Sort messages of current Rmail file by the name of the other correspondent.
`M-x rmail-sort-by-lines`
  Sort messages of current Rmail file by size (number of lines).
`M-x rmail-sort-by-keywords `RET` labels `RET``
  Sort messages of current Rmail file by labels. The argument labels should be a comma-separated list of labels. The order of these labels specifies the order of messages; messages with the first label come first, messages with the second label come second, and so on. Messages which have none of these labels come last.

The Rmail sort commands perform a stable sort: if there is no reason to prefer either one of two messages, their order remains unchanged. You can use this to sort by more than one criterion. For example, if you use `rmail-sort-by-date` and then `rmail-sort-by-author`, messages from the same author appear in order by date.

With a numeric argument, all these commands reverse the order of comparison. This means they sort messages from newest to oldest, from biggest to smallest, or in reverse alphabetical order.

## Display of Messages

Rmail reformats the header of each message before displaying it for the first time. Reformatting hides uninteresting header fields to reduce clutter. You can use the `t` command to show the entire header or to repeat the header reformatting operation.

`t`
  Toggle display of complete header (`rmail-toggle-header`).

Reformatting the header involves deleting most header fields, on the grounds that they are not interesting. The variable `rmail-ignored-headers` holds a regular expression that specifies which header fields to hide in this way--if it matches the beginning of a header field, that whole field is hidden.

Rmail saves the complete original header before reformatting; to see it, use the `t` command (`rmail-toggle-header`). This discards the reformatted headers of the current message and displays it with the original header. Repeating `t` reformats the message again. Selecting the message again also reformats.

One consequence of this is that if you edit the reformatted header (using `e`; see section Editing Within a Message), subsequent use of `t` will discard your edits. On the other hand, if you use `e` after `t`, to edit the original (unreformatted) header, those changes are permanent.

When used with a window system that supports multiple fonts, Rmail highlights certain header fields that are especially interesting--by default, the ``From'` and ``Subject'` fields. The variable `rmail-highlighted-headers` holds a regular expression that specifies the header fields to highlight; if it matches the beginning of a header field, that whole field is highlighted.

If you specify unusual colors for your text foreground and background, the colors used for highlighting may not go well with them. If so, specify different colors for the `highlight` face. That is worth doing because the `highlight` face is used for other kinds of highlighting as well. See section Using Multiple Typefaces, for how to do this.

To turn off highlighting entirely in Rmail, set `rmail-highlighted-headers` to `nil`.

## Editing Within a Message

Most of the usual Emacs commands are available in Rmail mode, though a few, such as `C-M-n` and `C-M-h`, are redefined by Rmail for other purposes. However, the Rmail buffer is normally read only, and most of the letters are redefined as Rmail commands. If you want to edit the text of a message, you must use the Rmail command `e`.

`e`
  Edit the current message as ordinary text.

The `e` command (`rmail-edit-current-message`) switches from Rmail mode into Rmail Edit mode, another major mode which is nearly the same as Text mode. The mode line indicates this change.

In Rmail Edit mode, letters insert themselves as usual and the Rmail commands are not available. When you are finished editing the message and are ready to go back to Rmail, type `C-c C-c`, which switches back to Rmail mode. Alternatively, you can return to Rmail mode but cancel all the editing that you have done, by typing `C-c C-]`.

Entering Rmail Edit mode runs the hook `text-mode-hook`; then it runs the hook `rmail-edit-mode-hook` (see section Hooks). It adds the attribute ``edited'` to the message.

## Digest Messages

A digest message is a message which exists to contain and carry several other messages. Digests are used on some moderated mailing lists; all the messages that arrive for the list during a period of time such as one day are put inside a single digest which is then sent to the subscribers. Transmitting the single digest uses much less computer time than transmitting the individual messages even though the total size is the same, because the per-message overhead in network mail transmission is considerable.

When you receive a digest message, the most convenient way to read it is to undigestify it: to turn it back into many individual messages. Then you can read and delete the individual messages as it suits you.

To do this, select the digest message and type the command `M-x undigestify-rmail-message`. This extracts the submessages as separate Rmail messages, and inserts them following the digest. The digest message itself is flagged as deleted.

## Converting an Rmail File to Inbox Format

The command `M-x unrmail` converts a file in Rmail format to inbox format (also known as the system mailbox format), so that you can use it with other mail-editing tools. You must specify two arguments, the name of the Rmail file and the name to use for the converted file. `M-x unrmail` does not alter the Rmail file itself.

## Reading Rot13 Messages

Mailing list messages that might offend some readers are sometimes encoded in a simple code called rot13---so named because it rotates the alphabet by 13 letters. This code is not for secrecy, as it provides none; rather, it enables those who might be offended to avoid ever seeing the real text of the message.

To view a buffer using the rot13 code, use the command `M-x rot13-other-window`. This displays the current buffer in another window which applies the code when displaying the text.

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