Mutt has a built-in line editor for inputting text, e.g. email addresses or filenames. The keys used to manipulate text input are very similar to those of Emacs. See Table 2.2, “Most common line editor keys” for a full reference of available functions, their default key bindings, and short descriptions.

You can remap the editor functions using the bind command. For example, to make the Delete key delete the character in front of the cursor rather than under, you could use

bind editor <delete> backspace

The number of items in the built-in editor's history is controlled by the $history variable. You may cycle through them at an editor prompt by using the history-up and/or history-down commands.

Mutt maintains several distinct history lists, one for each of the following categories:

Mutt automatically filters out repeated items from the history. It also mimics the behavior of some shells by ignoring items starting with a space.

The latter feature can be useful in macros to not clobber the history's valuable entries with unwanted entries.

Common keys used to navigate through and manage messages in the index are shown in Table 2.3, “Most common message index keys”.

By default, Mutt uses its builtin pager to display the body of messages. The pager is very similar to the Unix program less though not nearly as featureful.

In addition to key bindings in Table 2.4, “Most common pager keys”, many of the functions from the index are available in the pager, such as delete-message or copy-message (this is one advantage over using an external pager to view messages).

Also, the internal pager supports a couple other advanced features. For one, it will accept and translate the ``standard'' nroff sequences for bold and underline. These sequences are a series of either the letter, backspace (^H), the letter again for bold or the letter, backspace, ``_'' for denoting underline. Mutt will attempt to display these in bold and underline respectively if your terminal supports them. If not, you can use the bold and underline color objects to specify a color or mono attribute for them.

Additionally, the internal pager supports the ANSI escape sequences for character attributes. Mutt translates them into the correct color and character settings. The sequences Mutt supports are '\e[Ps;Ps;..Ps;m' where Ps can be one of the codes shown in Table 2.5, “ANSI escape sequences”.

Mutt uses these attributes for handling text/enriched messages, and they can also be used by an external autoview script for highlighting purposes. Note: If you change the colors for your display, for example by changing the color associated with color2 for your xterm, then that color will be used instead of green.

When the mailbox is sorted by threads, there are a few additional functions available in the index and pager modes as shown in Table 2.7, “Most common thread mode keys”.

Note: Collapsing a thread displays only the first message in the thread and hides the others. This is useful when threads contain so many messages that you can only see a handful of threads on the screen. See %M in $index_format. For example, you could use "%?M?(#%03M)&(%4l)?" in $index_format to optionally display the number of hidden messages if the thread is collapsed.

See also: $strict_threads.

create-alias (default: a)

Creates a new alias based upon the current message (or prompts for a new one). Once editing is complete, an alias command is added to the file specified by the $alias_file variable for future use. Note: Specifying an $alias_file does not add the aliases specified there-in, you must also source the file.

check-traditional-pgp (default: ESC P)

This function will search the current message for content signed or encrypted with PGP the "traditional" way, that is, without proper MIME tagging. Technically, this function will temporarily change the MIME content types of the body parts containing PGP data; this is similar to the edit-type function's effect.

display-toggle-weed (default: h)

Toggles the weeding of message header fields specified by ignore commands.

edit (default: e)

This command (available in the ``index'' and ``pager'') allows you to edit the raw current message as it's present in the mail folder. After you have finished editing, the changed message will be appended to the current folder, and the original message will be marked for deletion.

edit-type (default: ^E on the attachment menu, and in the pager and index menus; ^T on the compose menu)

This command is used to temporarily edit an attachment's content type to fix, for instance, bogus character set parameters. When invoked from the index or from the pager, you'll have the opportunity to edit the top-level attachment's content type. On the attachment menu, you can change any attachment's content type. These changes are not persistent, and get lost upon changing folders.

Note that this command is also available on the compose menu. There, it's used to fine-tune the properties of attachments you are going to send.

enter-command (default: ``:'')

This command is used to execute any command you would normally put in a configuration file. A common use is to check the settings of variables, or in conjunction with macros to change settings on the fly.

extract-keys (default: ^K)

This command extracts PGP public keys from the current or tagged message(s) and adds them to your PGP public key ring.

forget-passphrase (default: ^F)

This command wipes the passphrase(s) from memory. It is useful, if you misspelled the passphrase.

list-reply (default: L)

Reply to the current or tagged message(s) by extracting any addresses which match the regular expressions given by the lists or subscribe commands, but also honor any Mail-Followup-To header(s) if the $honor_followup_to configuration variable is set. Using this when replying to messages posted to mailing lists helps avoid duplicate copies being sent to the author of the message you are replying to.

pipe-message (default: |)

Asks for an external Unix command and pipes the current or tagged message(s) to it. The variables $pipe_decode, $pipe_split, $pipe_sep and $wait_key control the exact behavior of this function.

resend-message (default: ESC e)

With resend-message, mutt takes the current message as a template for a new message. This function is best described as "recall from arbitrary folders". It can conveniently be used to forward MIME messages while preserving the original mail structure. Note that the amount of headers included here depends on the value of the $weed variable.

This function is also available from the attachment menu. You can use this to easily resend a message which was included with a bounce message as a message/rfc822 body part.

shell-escape (default: !)

Asks for an external Unix command and executes it. The $wait_key can be used to control whether Mutt will wait for a key to be pressed when the command returns (presumably to let the user read the output of the command), based on the return status of the named command.

toggle-quoted (default: T)

The pager uses the $quote_regexp variable to detect quoted text when displaying the body of the message. This function toggles the display of the quoted material in the message. It is particularly useful when are interested in just the response and there is a large amount of quoted text in the way.

skip-quoted (default: S)

This function will go to the next line of non-quoted text which come after a line of quoted text in the internal pager.

When editing the header of your outgoing message, there are a couple of special features available.

If you specify Fcc: filename Mutt will pick up filename just as if you had used the edit-fcc function in the compose menu.

You can also attach files to your message by specifying Attach: filename [ description ] where filename is the file to attach and description is an optional string to use as the description of the attached file.

When replying to messages, if you remove the In-Reply-To: field from the header field, Mutt will not generate a References: field, which allows you to create a new message thread.

Also see $edit_headers.

If you want to use PGP, you can specify

Pgp: [ E | S | S<id> ]

``E'' encrypts, ``S'' signs and ``S<id>'' signs with the given key, setting $pgp_sign_as permanently.

If you have told mutt to PGP encrypt a message, it will guide you through a key selection process when you try to send the message. Mutt will not ask you any questions about keys which have a certified user ID matching one of the message recipients' mail addresses. However, there may be situations in which there are several keys, weakly certified user ID fields, or where no matching keys can be found.

In these cases, you are dropped into a menu with a list of keys from which you can select one. When you quit this menu, or mutt can't find any matching keys, you are prompted for a user ID. You can, as usually, abort this prompt using ^G. When you do so, mutt will return to the compose screen.

Once you have successfully finished the key selection, the message will be encrypted using the selected public keys, and sent out.

Most fields of the entries in the key selection menu (see also $pgp_entry_format) have obvious meanings. But some explanations on the capabilities, flags, and validity fields are in order.

The flags sequence (%f) will expand to one of the flags in Table 2.10, “PGP key menu flags”.

The capabilities field (%c) expands to a two-character sequence representing a key's capabilities. The first character gives the key's encryption capabilities: A minus sign (-) means that the key cannot be used for encryption. A dot (.) means that it's marked as a signature key in one of the user IDs, but may also be used for encryption. The letter e indicates that this key can be used for encryption.

The second character indicates the key's signing capabilities. Once again, a ``-'' implies ``not for signing'', ``.'' implies that the key is marked as an encryption key in one of the user-ids, and ``s'' denotes a key which can be used for signing.

Finally, the validity field (%t) indicates how well-certified a user-id is. A question mark (?) indicates undefined validity, a minus character (-) marks an untrusted association, a space character means a partially trusted association, and a plus character (+) indicates complete validity.

You may also have configured mutt to co-operate with Mixmaster, an anonymous remailer. Mixmaster permits you to send your messages anonymously using a chain of remailers. Mixmaster support in mutt is for mixmaster version 2.04 (beta 45 appears to be the latest) and 2.03. It does not support earlier versions or the later so-called version 3 betas, of which the latest appears to be called 2.9b23.

To use it, you'll have to obey certain restrictions. Most important, you cannot use the Cc and Bcc headers. To tell Mutt to use mixmaster, you have to select a remailer chain, using the mix function on the compose menu.

The chain selection screen is divided into two parts. In the (larger) upper part, you get a list of remailers you may use. In the lower part, you see the currently selected chain of remailers.

You can navigate in the chain using the chain-prev and chain-next functions, which are by default bound to the left and right arrows and to the h and l keys (think vi keyboard bindings). To insert a remailer at the current chain position, use the insert function. To append a remailer behind the current chain position, use select-entry or append. You can also delete entries from the chain, using the corresponding function. Finally, to abandon your changes, leave the menu, or accept them pressing (by default) the Return key.

Note that different remailers do have different capabilities, indicated in the %c entry of the remailer menu lines (see $mix_entry_format). Most important is the ``middleman'' capability, indicated by a capital ``M'': This means that the remailer in question cannot be used as the final element of a chain, but will only forward messages to other mixmaster remailers. For details on the other capabilities, please have a look at the mixmaster documentation.