NAIL(1)

NAME
nail - send and receive MIME conformant mail

SYNOPSIS
nail [-BDFintv~] [-s subject] [-a attachment ] [-c cc-addr] [-b bcc-addr] [-r from-addr] [-h hops] [-A account] to-addr . . .
nail [-BDeHiInNv~] [-T name] [-A account] -f [name]
nail [-BDeinNv~] [-A account] [-u user]

DESCRIPTION
Nail is an intelligent mail processing system, which has a command syntax reminiscent of ed(1) with lines replaced by messages. It is based on Berkeley Mail 8.1, is intended to provide the functionality of the POSIX mailx command, and offers extensions for MIME messages, IMAP, POP3 and SMTP.

The following options are accepted:

-A name
    Executes an account command (see below) for name after the startup files have been read.

-a file
    Attach the given file to the message.

-B  Make standard input and standard output line-buffered.

-b address
    Send blind carbon copies to list. List should be a comma-separated list of names.

-c address
    Send carbon copies to list of users.

-D  Start in disconnected mode; see the description for the disconnected variable option.

-e  Just check if mail is present in the system mailbox. If yes, return an exit status of zero, else, a non-zero value.

-f [file]
    Read in the contents of your mbox (or the specified file) for processing; when you quit, nail writes undeleted messages back to this file. The string file is handled as described for the folder command below.

-F  Save the message to send in a file named after the local part of the first recipient's address.

-H  Print header summaries for all messages and exit.

-h hops
    Invoke sendmail with the specified hop count. This option has no effect when SMTP is used for sending mail.

-i  Ignore tty interrupt signals. This is particularly useful when using nail on noisy phone lines.

-I  Shows the `Newsgroup:' or `Article-Id:' fields in the header summary. Only applicable in combination with -f.

-n  Inhibits reading /etc/mail.rc upon startup.

-N  Inhibits the initial display of message headers when reading mail or editing a mail folder.

-q file
    Start the message with the contents of the specified file. May be given in send mode only.

-r address
    Sets the From address. Overrides any from variable specified in environment or startup files. Tilde escapes are disabled. The -r address options are passed to the mail transfer agent unless SMTP is used.

-s subject
    Specify subject on command line (only the first argument after the -s flag is used as a subject; be careful to quote subjects containing spaces).

-R address
    Specify reply-to adress on command line. Only the first argument after the -R flag is used as the address.

-T name
    Writes the `Message-Id' and `Article-Id' header fields of each message read in the file name. Implies -I. Compressed files are handled as described for the folder command below.

-t  The message to be sent is expected to contain a message header with `To:', `Cc:', or `Bcc:' fields giving its recipients. Recipients specified on the command line are ignored.

-u user
    Reads the mailbox of the given user name.

-v  Verbose mode. The details of delivery are displayed on the user's terminal.

-V  Print nail's version and exit.

-~  Enable tilde escapes even if not in interactive mode.

  Sending mail
To send a message to one or more people, nail can be invoked with arguments which are the names of people to whom the mail will be sent. You are then expected to type in your message, followed by an `control-D' at the beginning of a line. The section below Replying to or originating mail, describes some features of nail available to help you compose your letter.

  Reading mail
In normal usage nail is given no arguments and checks your mail out of the post office, then prints out a one line header of each message found. The current message is initially the first message (numbered 1) and can be printed using the print command which can be abbreviated `p'). You can move among the messages much as you move between lines in ed(1), with the commands `+' and `-' moving backwards and forwards, and simple numbers.

  Disposing of mail
After examining a message you can delete `d') the message or reply `r') to it. Deletion causes the nail program to forget about the message. This is not irreversible; the message can be undeleted `u') by giving its number, or the nail session can be aborted by giving the exit `x') command. Deleted messages will, however, usually disappear never to be seen again.

  Specifying messages
Commands such as print and delete can be given a list of message numbers as arguments to apply to a number of messages at once. Thus `delete 1 2' deletes messages 1 and 2, while `delete 1-5' deletes messages 1 through 5. In sorted or threaded mode (see the sort and thread commands), `delete 1-5' deletes the messages that are located between (and including) messages 1 through 5 in the sorted/threaded order, as shown in the header summary. The following special message names exist:

:n  All new messages.

:o  All old messages (any not in state read or new).

:u  All unread messages.

:d  All deleted messages.

:r  All read messages.

/string
    All messages that contain string in the subject field (case ignored).

address
    All messages from address.

.   The current message.

;   The message that was previously the current message.

,   The parent message of the current message, that is the message with the Message-ID given in the `In-Reply-To:' field or the last entry of the `References:' field of the current message.

-   The next previous undeleted message, or the next previous deleted message for the undelete command. In sorted/threaded mode, the next previous such message in the sorted/threaded order.

+   The next undeleted message, or the next deleted message for the undelete command. In sorted/threaded mode, the next such message in the sorted/threaded order.

^   The first undeleted message, or the first deleted message for the undelete command. In sorted/threaded mode, the first such message in the sorted/threaded order.

$   The last message. In sorted/threaded mode, the last message in the sorted/threaded order.

&x  Only recognized in threaded mode; selects the message addressed with x, where x is any other message specification, and all messages from the thread that begins at it. If n is omitted, the thread beginning with the current message is selected.

*   All messages.

  Replying to or originating mail
You can use the reply command to set up a response to a message, sending it back to the person who it was from. Text you then type in, up to an end-of-file, defines the contents of the message. While you are composing a message, nail treats lines beginning with the character `~' specially. For instance, typing `~m' (alone on a line) will place a copy of the current message into the response right shifting it by a tabstop (see indentprefix variable, below). Other escapes will set up subject fields, add and delete recipients to the message, attach files to it and allow you to escape to an editor to revise the message or to a shell to run some commands. (These options are given in the summary below.)

  Ending a mail processing session
You can end a nail session with the quit `q') command. Messages which have been examined go to your mbox file unless they have been deleted in which case they are discarded. Unexamined messages go back to the post office. (See the -f option above).

  Personal and systemwide distribution lists
It is also possible to create a personal distribution lists so that, for instance, you can send mail to `cohorts' and have it go to a group of people. Such lists can be defined by placing a line like
        alias cohorts bill ozalp jkf mark kridle@ucbcory
in the file .mailrc in your home directory. The current list of such aliases can be displayed with the alias command in nail. System wide distribution lists can be created by editing /etc/aliases, see aliases(5) and sendmail(8); these are kept in a different syntax. In mail you send, personal aliases will be expanded in mail sent to others so that they will be able to reply to the recipients. System wide aliases are not expanded when the mail is sent, but any reply returned to the machine will have the system wide alias expanded as all mail goes through sendmail.

  Recipient address specifications
When an address is used to name a recipient (in any of To, Cc, or Bcc), names of local mail folders and pipes to external commands can also be specified; the message text is then written to them. The rules are: Any name which starts with a `|' character specifies a pipe, the command string following the `|' is executed and the message is sent to its standard input; any other name which contains a `@' character is treated as a mail address; any other name which starts with a `+' character specifies a folder name; any other name which contains a `/' character but no `!' or `%' character before also specifies a folder name; what remains is treated as a mail address. Compressed folders are handled as described for the folder command below.

  Network mail (Internet / ARPA, UUCP, Berknet)
See mailaddr(7) for a description of network addresses. Nail has a number of options which can be set in the .mailrc file to alter its behavior; thus `set askcc' enables the askcc feature. (These options are summarized below).

  MIME types
For any outgoing attachment, nail tries to determine the content type. It does this by reading MIME type files whose lines have the following syntax:
        type/subtype      extension [extension . . .]
where type/subtype are strings describing the file contents, and extension is the part of a filename starting after the last dot. Any line not immediately beginning with an ASCII alphabetical character is ignored by nail. If there is a match with the extension of the file to attach, the given type/subtype pair is used. Otherwise, or if the filename has no extension, the content types text/plain or application/octet-stream are used, the first for text or international text files, the second for any file that contains formatting characters other than newlines and horizontal tabulators.

  Locale
Nail uses the LC_CTYPE locale setting to determine whether a character is printable. Thus, its value has to match the character set of the terminal nail runs on.

  Character sets
If a message contains non-ASCII characters, the character set being used must be declared within the header. Its value can be declared using the charset variable. It is normally assumed that this is the terminal character set, too. If the latter differs from the one that should be used in outgoing mail, the ttycharset variable can be used for its declaration. An outgoing message is then converted, resulting in errors when this process cannot be done for the entire text; if the message contains NUL characters, it is not converted. Attachments are never converted. Any message that is displayed on a terminal is tried to convert, too, with characters not in the terminal character set replaced by question marks.

  Commands
Each command is typed on a line by itself, and may take arguments following the command word. The command need not be typed in its entirety – the first command which matches the typed prefix is used. For commands which take message lists as arguments, if no message list is given, then the next message forward which satisfies the command's requirements is used. If there are no messages forward of the current message, the search proceeds backwards, and if there are no good messages at all, nail types `applicable messages' and aborts the command. If the command begins with a # sign, the line is ignored.

The arguments to commands can be quoted, using the following methods:

•   An argument can be enclosed between paired double-quotes "" or single-quotes ''; any white space, shell word expansion, or backslash characters within the quotes are treated literally as part of the argument. A double-quote will be treated literally within single-quotes and vice versa. These special properties of the quote marks occur only when they are paired at the beginning and end of the argument.

•   A backslash outside of the enclosing quotes is discarded and the following character is treated literally as part of the argument.

•   An unquoted backslash at the end of a command line is discarded and the next line continues the command.

Filenames, where expected, are subjected to the following transformations, in sequence:

•   If the filename begins with an unquoted plus sign, and the folder variable is defined, the plus sign will be replaced by the value of the folder variable followed by a slash. If the folder variable is unset or is set to null, the filename will be unchanged.

•   Shell word expansions are applied to the filename. If more than a single pathname results from this expansion and the command is expecting one file, an error results.

The following commands are provided:

-   Print out the preceding message. If given a numeric argument n, goes to the n'th previous message and prints it.

?   Prints a brief summary of commands.

!   Executes the shell (see sh(1) and csh(1)) command which follows.

|   A synonym for the pipe command.

account
    (ac) Creates, selects or lists an email account. An account is formed by a group of variables. With two or more arguments, the first argument gives an account name, and the following arguments create a group of variables. With one argument, the previously created group of variables for the account name is activated as described for the set command, and a folder command is executed for the system mailbox or inbox of that account. Without arguments, the list of accounts is printed. As an example,

        account myisp \
            folder=imaps://mylogin@imap.myisp.example \
            record=+Sent \
            from="myname@myisp.example (My Name)" \
            smtp=smtp.myisp.example

    creates an account named `myisp' which can later be selected by specifying `account myisp'.

alias
    (a) With no arguments, prints out all currently-defined aliases. With one argument, prints out that alias. With more than one argument, creates a new alias or changes an old one.

alternates
    (alt) The alternates command is useful if you have accounts on several machines. It can be used to inform nail that the listed addresses are really you. When you reply to messages, nail will not send a copy of the message to any of the addresses listed on the alternates list. If the alternates command is given with no argument, the current set of alternate names is displayed.

cache
    Only applicable to cached IMAP mailboxes; takes a message list and reads the specified messages into the IMAP cache.

cd  Same as chdir.

chdir
    (ch) Changes the user's working directory to that specified, if given. If no directory is given, then changes to the user's login directory.

connect
    (conn) If operating in disconnected mode on an IMAP mailbox, switch to online mode and connect to the mail server while retaining the mailbox status. See the description of the disconnected variable for more information.

copy
    (c) The copy command does the same thing that save does, except that it does not mark the messages it is used on for deletion when you quit. Compressed files and IMAP mailboxes are handled as described for the folder command.

Copy
    (C) Similar to copy, but saves the messages in a file named after the local part of the sender address of the first message.

delete
    (d) Takes a list of messages as argument and marks them all as deleted. Deleted messages will not be saved in mbox, nor will they be available for most other commands.

discard
    Same as ignore.

disconnect
    (disco) If operating in online mode on an IMAP mailbox, switch to disconnected mode while retaining the mailbox status. See the description of the disconnected variable for more information. A list of messages may optionally be given as argument; the respective messages are then read into the cache before the connection is closed. Thus `disco *' makes the entire current mailbox available for disconnected use.

dp or dt
    Deletes the current message and prints the next message. If there is no next message, nail says `at EOF'.

echo
    Echoes its arguments, resolving special names as documented for the folder command. The escape sequences `\a', `\b', `\c', `\f', `\n', `\r', `\t', `\v', `\\', and `\0num' are interpreted as with the echo(1) command.

edit
    (e) Takes a list of messages and points the text editor at each one in turn. On return from the editor, the message is read back in.

else
    Marks the end of the then-part of an if statement and the beginning of the part to take effect if the condition of the if statement is false.

endif
    Marks the end of an if statement.

exit
    (ex or x) Effects an immediate return to the Shell without modifying the user's system mailbox, his mbox file, or his edit file in -f.

file
    (fi) The same as folder.

folders
    List the names of the folders in your folder directory.

folder
    (fold) The folder command switches to a new mail file or folder. With no arguments, it tells you which file you are currently reading. If you give it an argument, it will write out changes (such as deletions) you have made in the current file and read in the new file. Some special conventions are recognized for the name. # means the previous file, % means your system mailbox, %user means user's system mailbox, & means your mbox file, and +file means a file in your folder directory. %:filespec expands to the same value as filespec, but the file is handled as a system mailbox e. g. by the mbox and save commands. If the name matches one of the strings defined with the shortcut command, it is replaced by its long form and expanded. If the name ends with .gz or .bz2, it is treated as compressed with gzip(1) or bzip2(1), respectively. Likewise, if name does not exist, but either name.gz or name.bz2 exists, the compressed file is used. A name of the form
           protocol://[user@]host[:port][/file]
    is taken as an Internet mailbox specification. The supported protocols are currently imap (IMAP v4r1), imaps (IMAP with SSL/TLS encryption), pop3 (POP3), and pop3s (POP3 with SSL/TLS encryption). The optional file part applies to IMAP only; if it is omitted, the default `INBOX' is used. If nail is connected to an IMAP server, a name of the form @mailbox refers to the mailbox on that server. If the `folder' variable refers to an IMAP account, the special name `%' selects the `INBOX' on that account.

Followup
    (F) Similar to Respond, but saves the message in a file named after the local part of the first recipient's address.

followup
    (fo) Similar to respond, but saves the message in a file named after the local part of the first recipient's address.

followupall
    Similar to followup, but responds to all recipients regardless of the flipr and Replyall variables.

followupsender
    Similar to Followup, but responds to the sender only regardless of the flipr and Replyall variables.

Forward
    (For) Like forward, but does not add any header lines. This is not a way to hide the sender's identity, but useful for sending a message again to the same recipients.

forward
    (for) Takes a list of messages and a user name and sends each message to the named user.

from
    (f) Takes a list of messages and prints their message headers, piped through the pager if the output does not fit on the screen.

headers
    (h) Lists the current range of headers, which is an 18-message group. If a `+' argument is given, then the next 18-message group is printed, and if a `-' argument is given, the previous 18-message group is printed.

help
    A synonym for ?.

hold
    (ho, also preserve) Takes a message list and marks each message therein to be saved in the user's system mailbox instead of in mbox. Does not override the delete command. nail deviates from the POSIX standard with this command, as a `next' command issued after `hold' will display the following message, not the current one.

if  Commands in nail's startup files can be executed conditionally depending on whether you are sending or receiving mail with the if command. For example, you can do:
            if receive
                    commands . . .
            endif
    An else form is also available:
            if receive
                    commands . . .
            else
                    commands . . .
            endif
    Note that the only allowed conditions are receive, send, and term (execute command if standard input is a tty).

ignore
    Add the list of header fields named to the ignored list. Header fields in the ignore list are not printed on your terminal when you print a message. This command is very handy for suppression of certain machine-generated header fields. The Type and Print commands can be used to print a message in its entirety, including ignored fields. If ignore is executed with no arguments, it lists the current set of ignored fields.

imap
    Sends command strings directly to the current IMAP server. Nail operates always in IMAP selected state on the current mailbox; commands that change this will produce undesirable results and should be avoided. Useful IMAP commands are:

    create
        Takes the name of an IMAP mailbox as an argument and creates it.

    delete
        Takes the name of an IMAP mailbox as an argument and deletes it.

    getquotaroot
        Takes the name of an IMAP mailbox as an argument and prints the quotas that apply to the mailbox. Not all IMAP servers support this command.

    list
        Takes two arguments, a reference name which specifies the desired hierarchy, and a mailbox name with possible wildcards. To get a list of all existing IMAP mailboxes, use `imap list "" *'.

    namespace
        Takes no arguments and prints the Personal Namespaces, the Other User's Namespaces, and the Shared Namespaces. Each namespace type is printed in parentheses; if there are multiple namespaces of the same type, inner parentheses separate them. For each namespace, a namespace prefix and a hierarchy separator is listed. Not all IMAP servers support this command.

    rename
        Takes the name of an existing IMAP mailbox as the first argument and renames it to the name given as second argument.

    search
        Searches for messages that match the criteria given as arguments and prints their IMAP message numbers. For example, `imap search body string' looks for all messages which contain string in their body.

    IMAP message numbers are usually identical to regular message numbers, but can change when a message is deleted on the server by another client or process. They should thus be used with care; if in doubt, use a `print' command to verify them. The problem does not occur with regular message numbers because nail internally uses IMAP unique identifiers (UIDs) to refer to them.

inc Same as newmail.

list
    Prints the names of all available commands.

Mail
    (M) Similar to mail, but saves the message in a file named after the local part of the first recipient's address.

mail
    (m) Takes as argument login names and distribution group names and sends mail to those people.

mbox
    Indicate that a list of messages be sent to mbox in your home directory when you quit. This is the default action for messages if you do not have the hold option set.

newmail
    Checks for new mail in the current folder without committing any changes before. If new mail is present, a message is printed. If the header variable is set, the headers of each new message are also printed.

next
    (n) like + or CR) Goes to the next message in sequence and types it. With an argument list, types the next matching message.

New Same as unread.

new Same as unread.

online
    Same as connect.

preserve
    (pre) A synonym for hold.

Pipe
    (Pi) Like pipe but also pipes ignored header fields.

pipe
    (pi) Takes a message list and a shell command and pipes the messages through the command. Without an argument, the current message is piped through the command given by the cmd variable. If the page variable is set, every message is followed by a formfeed character.

Print
    (P) Like print but also prints out ignored header fields. See also print, ignore, and retain.

print
    (p) Takes a message list and types out each message on the user's terminal. If the message is a MIME multipart message, all parts with a content type of `text' or `message' are shown, the other are hidden except for their headers.

quit
    (q) Terminates the session, saving all undeleted, unsaved messages in the user's mbox file in his login directory, preserving all messages marked with hold or preserve or never referenced in his system mailbox, and removing all other messages from his system mailbox. If new mail has arrived during the session, the message `You have new mail' is given. If given while editing a mailbox file with the -f flag, then the edit file is rewritten. A return to the Shell is effected, unless the rewrite of edit file fails, in which case the user can escape with the exit command.

Reply
    (R) Reply to originator. Does not reply to other recipients of the original message.

reply
    (r) Takes a message list and sends mail to the sender and all recipients of the specified message. The default message must not be deleted.

replyall
    Similar to reply, but responds to all recipients regardless of the flipr and Replyall variables.

replysender
    Similar to Reply, but responds to the sender only regardless of the flipr and Replyall variables.

Respond
    Same as Reply.

respond
    Same as reply.

respondall
    Same as replyall.

respondsender
    Same as replysender.

retain
    Add the list of header fields named to the retained list. Only the header fields in the retain list are shown on your terminal when you print a message. All other header fields are suppressed. The Type and Print commands can be used to print a message in its entirety. If retain is executed with no arguments, it lists the current set of retained fields.

Save
    (S) Similar to save, but saves the messages in a file named after the local part of the sender of the first message instead of taking a filename argument.

save
    (s) Takes a message list and a filename and appends each message in turn to the end of the file. If no filename is given, the mbox file is used. The filename in quotes, followed by the line count and character count is echoed on the user's terminal. If editing a system mailbox, the messages are marked for deletion. Compressed files and IMAP mailboxes are handled as described for the -f command line option above.

savediscard
    Same as saveignore.

saveignore
    Saveignore is to save what ignore is to print and type. Header fields thus marked are filtered out when saving a message by save or when automatically saving to mbox. This command should only be applied to header fields that do not contain information needed to decode the message, as MIME content fields do. If saving messages on an IMAP account, ignoring fields makes it impossible to copy the data directly on the server, thus operation usually becomes much slower.

saveretain
    Saveretain is to save what retain is to print and type. Header fields thus marked are the only ones saved with a message when saving by save or when automatically saving to mbox. Saveretain overrides saveignore. The use of this command is strongly discouraged since it may strip header fields that are needed to decode the message correctly.

set (se) With no arguments, prints all variable values, piped through the pager if the output does not fit on the screen. Otherwise, sets option. Arguments are of the form option=value (no space before or after =) or option. Quotation marks may be placed around any part of the assignment statement to quote blanks or tabs, i.e. `set indentprefix="->"'. If an argument begins with no, as in `set nosave', the effect is the same as invoking the unset command with the remaining part of the variable (`unset save').

shell
    (sh) Invokes an interactive version of the shell.

shortcut
    Defines a shortcut name and its string for expansion, as described for the folder command. With no arguments, a list of defined shortcuts is printed.

size
    Takes a message list and prints out the size in characters of each message.

sort
    Create a sorted representation of the current folder, and change the next command and the addressing modes such that they refer to messages in the sorted order. Message numbers are the same as in regular mode. If the header variable is set, a header summary in the new order is also printed. Possible sorting criteria are:

    date
        Sort the messages by their `Date:' field, that is by the time they were sent.

    from
        Sort messages by the value of their `From:' field, that is by the address of the sender. If the showname variable is set, the sender's real name (if any) is used.

    size
        Sort the messages by their size.

    status
        Sort the messages by their message status (new, read, old, etc.).

    subject
        Sort the messages by their subject.

    thread
        Create a threaded order, as with the thread command.

    to  Sort messages by the value of their `To:' field, that is by the address of the recipient. If the showname variable is set, the recipient's real name (if any) is used.

    If no argument is given, the current sorting criterion is printed.

source
    The source command reads commands from a file.

thread
    (th) Create a threaded representation of the current folder, i.e. indent messages that are replies to other messages in the header display, and change the next command and the addressing modes such that they refer to messages in the threaded order. Message numbers are the same as in unthreaded mode. If the header variable is set, a header summary in threaded order is also printed.

top Takes a message list and prints the top few lines of each. The number of lines printed is controlled by the variable toplines and defaults to five.

touch
    Takes a message list and marks the messages for saving in the mbox file.

Type
    (T) Identical to the Print command.

type
    (t) A synonym for print.

unalias
    Takes a list of names defined by alias commands and discards the remembered groups of users. The group names no longer have any significance.

undelete
    (u) Takes a message list and marks each message as not being deleted.

unignore
    Removes the header field names from the list of ignored fields.

Unread
    Same as unread.

unread
    (U) Takes a message list and marks each message as not having been read.

unretain
    Removes the header field names from the list of retained fields.

unsaveignore
    Removes the header field names from the list of ignored fields for saving.

unsaveretain
    Removes the header field names from the list of retained fields for saving.

unset
    Takes a list of option names and discards their remembered values; the inverse of set.

unshortcut
    Deletes the shortcut names given as arguments.

unsort
    Disable sorted or threaded mode (see the sort and thread commands), return to normal message order and, if the header variable is set, print a header summary.

unthread
    (unth) Same as unsort.

visual
    (v) Takes a message list and invokes the display editor on each message.

write
    (w) For conventional messages, the body without all headers is written. The output is converted to its native format, if necessary. If the output file exists, the text is appended.—If a message is in MIME multipart format, its first part is written to the specified file as for conventional messages, and the user is asked for a filename to save each other part; if the contents of the first part are not to be saved, `write /dev/null' can be used. In non-interactive mode, only the parts of the multipart message that have a filename given in the part header are written, the other are discarded. The original message is never marked for deletion in the originating mail folder. For attachments, the contents of the destination file are overwritten if the file previously existed. No special handling of compressed files is performed.

xit (x) A synonym for exit.

z   Nail presents message headers in windowfuls as described under the headers command. The z command scrolls to the next window of messages. If an argument is given, it specifies the window to use. A number prefixed by `+' or `-' indicates that the window is calculated in relation to the current position. A number without a prefix specifies an absolute window number, and a `$' lets nail scroll to the last window of messages.

  Tilde escapes
Here is a summary of the tilde escapes, which are used when composing messages to perform special functions. Tilde escapes are only recognized at the beginning of lines. The name `tilde escape' is somewhat of a misnomer since the actual escape character can be set by the option escape.

~!command
    Execute the indicated shell command, then return to the message.

~.  Same effect as typing the end-of-file character.

~<filename
    Identical to ~r.

~<!command
    Command is executed using the shell. Its standard output is inserted into the message.

~@ [filename . . . ]
    With no arguments, edit the attachment list. First, the user can edit all existing attachment data. If an attachment's file name is left empty, that attachment is deleted from the list. When the end of the attachment list is reached, nail will ask for further attachments, until an empty file name is given. If filename arguments are specified, all of them are appended to the end of the attachment list. Filenames which contain white space can only be specified with the first method (no filename arguments).

~A  Inserts the string contained in the Sign variable (same as `~i Sign'). The escape sequences `\t' (tabulator) and `\n' (newline) are understood.

~a  Inserts the string contained in the sign variable (same as `~i sign'). The escape sequences `\t' (tabulator) and `\n' (newline) are understood.

~bname . . .
    Add the given names to the list of carbon copy recipients but do not make the names visible in the Cc: line (`blind' carbon copy).

~cname . . .
    Add the given names to the list of carbon copy recipients.

~d  Read the file `dead.letter' from your home directory into the message.

~e  Invoke the text editor on the message collected so far. After the editing session is finished, you may continue appending text to the message.

~fmessages
    Read the named messages into the message being sent. If no messages are specified, read in the current message. Message headers currently being ignored (by the ignore or retain command) are not included.

~Fmessages
    Identical to ~f, except all message headers are included.

~h  Edit the message header fields by typing each one in turn and allowing the user to append text to the end or modify the field by using the current terminal erase and kill characters.

~ivariable
    Insert the value of the specified variable into the message adding a newline character at the end. If the variable is unset or empty, the message remains unaltered. The escape sequences `\t' (tabulator) and `\n' (newline) are understood.

~mmessages
    Read the named messages into the message being sent, indented by a tab or by the value of indentprefix. If no messages are specified, read the current message. Message headers currently being ignored (by the ignore or retain command) are not included.

~Mmessages
    Identical to ~m, except all message headers are included.

~p  Print out the message collected so far, prefaced by the message header fields and followed by the attachment list, if any. If the message text is longer than the screen size, it is piped through the pager.

~q  Abort the message being sent, copying the message to `dead.letter' in your home directory if save is set.

~Rstring
    Use string as the Reply-To field.

~rfilename
    Read the named file into the message.

~sstring
    Cause the named string to become the current subject field.

~tname . . .
    Add the given names to the direct recipient list.

~v  Invoke an alternate editor (defined by the VISUAL option) on the message collected so far. Usually, the alternate editor will be a screen editor. After you quit the editor, you may resume appending text to the end of your message.

~wfilename
    Write the message onto the named file. If the file exists, the message is appended to it.

~x  Same as ~q, except that the message is not saved to the `dead.letter' file.

~|command
    Pipe the message through the command as a filter. If the command gives no output or terminates abnormally, retain the original text of the message. The command fmt(1) is often used as command to rejustify the message.

~:nail-command
    Execute the given nail command. Not all commands, however, are allowed.

~_nail-command
    Identical to ~:.

~~string
    Insert the string of text in the message prefaced by a single ~. If you have changed the escape character, then you should double that character in order to send it.

  Variable options
Options are controlled via set and unset commands, see their entries for a syntax description. An option is also set if it is passed to nail as part of the environment (this is not restricted to specific variables as in the POSIX standard). A value given in a startup file overrides a value imported from the environment. Options may be either binary, in which case it is only significant to see whether they are set or not; or string, in which case the actual value is of interest.

  Binary options

The binary options include the following:

allnet
    Causes only the local part to be evaluated when comparing addresses.

append
    Causes messages saved in mbox to be appended to the end rather than prepended. This should always be set.

ask or asksub
    Causes nail to prompt you for the subject of each message you send. If you respond with simply a newline, no subject field will be sent.

askatend
    Causes the prompts for `Cc:' and `Bcc:' lists to appear after the message has been edited.

askattach
    If set, nail asks for files to attach at the end of each message. Responding with a newline indicates not to include an attachment.

askcc
    Causes you to be prompted for additional carbon copy recipients (at the end of each message if askatend or bsdcompat is set). Responding with a newline indicates your satisfaction with the current list.

askbcc
    Causes you to be prompted for additional blind carbon copy recipients (at the end of each message if askatend or bsdcompat is set). Responding with a newline indicates your satisfaction with the current list.

autoinc
    Same as newmail.

autoprint
    Causes the delete command to behave like dp - thus, after deleting a message, the next one will be typed automatically.

autothread
    Causes threaded mode (see the thread command) to be entered automatically when a folder is opened.

bang
    Enables the substitution of `!' by the contents of the last command line in shell escapes.

bsdannounce
    Causes automatic display of a header summary after executing a folder command.

bsdcompat
    Sets some cosmetical features to traditional BSD style; has the same affect as setting `askatend' and all other variables prefixed with `bsd', setting prompt to `& ', and changing the default pager to more.

bsdflags
    Changes the letters printed in the first column of a header summary to traditional BSD style.

bsdheadline
    Changes the display of columns in a header summary to traditional BSD style.

bsdmsgs
    Changes some informational messages to traditional BSD style.

bsdorder
    Causes the `Subject:' field to appear immediately after the `To:' field in message headers and with the ~h tilde command.

bsdset
    Changes the output format of the set command to traditional BSD style.

datefield
    The date in a header summary is normally the date of the mailbox `From ' line of the message. If this variable is set, the date as given in the `Date:' header field is used, converted to local time.

debug
    Prints debugging messages and disables the actual delivery of messages.

disconnected
    When an IMAP mailbox is selected and this variable is set, no connection to the server is initiated. Instead, data is obtained from the local cache (see imap-cache). Mailboxes that are not present in the cache and messages that have not yet entirely been fetched from the server are not available; to fetch all messages in a mailbox at once, the command `copy * /dev/null' can be used while still in online mode. Changes that are made to IMAP mailboxes in disconnected mode are queued and committed later when a connection to that server is opened in online mode. This procedure is not completely reliable since it cannot be guaranteed that the IMAP unique identifiers (UIDs) on the server still match the ones in the cache at that time. Data is saved to `dead.letter' when this problem occurs.

disconnected-user@host
    The specified account is handled as described for the disconnected variable above, but other accounts are not affected.

dot The binary option dot causes nail to interpret a period alone on a line as the terminator of a message you are sending.

editheaders
    When a message is edited while being composed, its header is included in the editable text. `To:', `Cc:', `Bcc:', and `Subject:' fields are accepted within the header, other fields are ignored.

emptybox
    If set, an empty mailbox file is not removed. This may improve the interoperability with other mail user agents when using a common folder directory.

emptystart
    If the mailbox is empty, nail normally prints `No mail for user' and exits immediately. If this option is set, nail starts even with an empty mailbox.

flipr
    Exchanges the Respond with the respond commands and vice-versa.

fullnames
    When replying to a message, nail normally removes the comment parts of email addresses, which by convention contain the full names of the recipients. If this variable is set, such stripping is not performed, and comments are retained.

header
    Causes the header summary to be written at startup and after commands that affect the number of messages or the order of messages in the current folder; enabled by default.

hold
    This option is used to hold messages in the system mailbox by default.

ignore
    Causes interrupt signals from your terminal to be ignored and echoed as @'s.

ignoreeof
    An option related to dot is ignoreeof which makes nail refuse to accept a control-d as the end of a message. Ignoreeof also applies to nail command mode.

imap-use-starttls
    Causes nail to issue a STARTTLS command to make an unencrypted IMAP session SSL/TLS encrypted. This functionality is not supported by all servers, and is not used if the session is already encrypted by the IMAPS method.

imap-use-starttls-user@host
    Activates imap-use-starttls for a specific account.

keep
    This option causes nail to truncate your system mailbox instead of deleting it when it is empty. This should always be set, since it prevents malicious users from creating fake mail folders in a world-writable spool directory.

keepsave
    When you save a message, nail usually discards it from the originating folder when you quit. To retain all saved messages, set this option.

metoo
    Usually, when a group is expanded that contains the sender, the sender is removed from the expansion. Setting this option causes the sender to be included in the group.

newmail
    Checks for new mail in the current folder each time the prompt is printed. For IMAP mailboxes, the server is then polled for new mail, which may result in delayed operation if the connection to the server is slow.

    If this variable is set to the special value nopoll, the server is not actively asked for new mail, but new mail may still be detected and announced with any other IMAP command that is sent to the server.

    In any case, the IMAP server may send notifications about messages that have been deleted on the server by another process or client. In this case, `Expunged n messages' is printed regardless of this variable, and message numbers may have changed.

noheader
    Setting the option noheader is the same as giving the -N flag on the command line.

outfolder
    Causes the filename given in the record variable and the sender-based filenames for the Copy and Save commands to be interpreted relative to the directory given in the folder variable rather than to the current directory unless it is an absolute pathname.

page
    If set, each message the pipe command prints out is followed by a formfeed character.

piperaw
    Send messages to the pipe command without performing MIME and character set conversions.

pop3-use-apop
    If this variable is set, the APOP authentication method is used when a connection to a POP3 server is initiated. The advantage of this method over the usual USER/PASS authentication is that the password is not sent over the network in clear text. The connection fails if the server does not support the APOP command.

pop3-use-apop-user@host
    Enables pop3-use-apop for a specific account.

pop3-use-starttls
    Causes nail to issue a STLS command to make an unencrypted POP3 session SSL/TLS encrypted. This functionality is not supported by all servers, and is not used if the session is already encrypted by the POP3S method.

pop3-use-starttls-user@host
    Activates pop3-use-starttls for a specific account.

print-all-chars
    This option causes all characters to be considered printable. It is only effective if given in a startup file. With this option set, some character sequences in messages may put the user's terminal in an undefined state when printed; it should only be used as a last resort if no working system locale can be found.

quiet
    Suppresses the printing of the version when first invoked.

Replyall
    Reverses the sense of reply and Reply commands.

save
    When you abort a message with two RUBOUT (interrupt characters) nail copies the partial letter to the file `dead.letter' in your home directory. This option is set by default.

searchheaders
    If this option is set, then a message-list specifier in the form `/x:y' will expand to all messages containing the substring `y' in the header field `x'. The string search is case insensitive.

sendwait
    When sending a message, wait until the mail transfer agent exits before accepting further commands. If the mail transfer agent returns a non-zero exit status, the exit status of nail will also be non-zero.

showlast
    Setting this option causes nail to start at the last message instead of the first one when opening a mail folder.

showname
    Causes nail to use the sender's real name instead of the plain address in the header field summary and in message specifications.

showto
    Causes the recipient of the message to be shown in the header summary if the message was sent by the user.

smtp-use-starttls
    Causes nail to issue a STARTTLS command to make an SMTP session SSL/TLS encrypted. Not all servers support this command; because of common implementation defects, it cannot be automatically determined whether a server supports it or not.

ssl-no-default-ca
    Do not load the default CA locations to verify SSL/TLS server certificates.

ssl-v2-allow
    Accept SSLv2 connections. These are normally not allowed because this protocol version is insecure.

stealthmua
    Inhibits the generation of the `Message-Id:' and `User-Agent:' header fields that include obvious references to nail. There are two pitfalls associated with this: First, the message id of outgoing messages is not known anymore. Second, an expert may still use the remaining information in the header to track down the originating mail user agent.

verbose
    Setting the option verbose is the same as using the -v flag on the command line. When nail runs in verbose mode, details of the actual message delivery and protocol conversations for IMAP, POP3, and SMTP are displayed on the user's terminal. This is sometimes useful to debug problems with specific servers. Nail prints all data that is sent to remote servers in clear texts, including passwords, so care should be taken that no unauthorized option can view the screen if this option is enabled.

  String Options

The string options include the following:

autobcc
    Specifies a list of recipients to which a blind carbon copy of each outgoing message will be sent automatically.

autocc
    Specifies a list of recipients to which a carbon copy of each outgoing message will be sent automatically.

autosort
    Causes sorted mode (see the sort command) to be entered automatically with the value of this option as sorting method when a folder is opened.

charset
    The name of the character set used by nail. If unset, the encoding used by the current locale is used if not ASCII. If the encoding is ASCII, iso-8859-1 is the default. The character set of all outgoing messages that contain non-ASCII characters is declared using its value.

cmd The default value for the pipe command.

crt The valued option crt is used as a threshold to determine how long a message must be before PAGER is used to read it. If crt is set without a value, then the height of the terminal screen stored in the system is used to compute the threshold (see stty(1)).

DEAD
    The name of the file to use for saving aborted messages. This defaults to `dead.letter' in the user's home directory.

EDITOR
    Pathname of the text editor to use in the edit command and ~e escape. If not defined, then a default editor is used.

encoding
    The default MIME encoding to use in outgoing text messages and message parts. Valid values are 8bit or quoted-printable. The default is 8bit. In case the mail transfer system is not ESMTP compliant, quoted-printable should be used instead. If there is no need to encode a message, 7bit transfer mode is used, without regard to the value of this variable. Binary data is always encoded in base64 mode.

escape
    If defined, the first character of this option gives the character to use in the place of ~ to denote escapes.

folder
    The name of the directory to use for storing folders of messages. All folder names that begin with `+' refer to files below that directory. If the directory name begins with a `/', nail considers it to be an absolute pathname; otherwise, the folder directory is found relative to your home directory.

    The directory name may also refer to an IMAP account; any names that begin with `+' then refer to IMAP mailboxes on that account. An IMAP folder is normally given in the form

        imaps://mylogin@imap.myisp.example

    In this case, the `+' and `@' prefixes for folder names have the same effect (see the folder command).

    Some IMAP servers do not accept the creation of mailboxes in the hierarchy base; they require that they are created as subfolders of `INBOX'. With such servers, a folder name of the form

        imaps://mylogin@imap.myisp.example/INBOX.

    should be used (the last character is the server's hierarchy delimiter). Folder names prefixed by `+' will then refer to folders below `INBOX', while folder names prefixed by `@' refer to folders below the hierarchy base. See the imap namespace command for a method to detect the appropriate prefix and delimiter.

from
    The address to put into the `From:' field of the message header. If replying to a message, this address is handled as if it were in the alternates list. If the machine's hostname is not valid at the Internet (for example at a dialup machine), you have to set this variable or hostname to get correct Message-ID header fields.

hostname
    Use this string as hostname when expanding local addresses instead of the value obtained from uname(2) and getaddrinfo(3).

imap-auth
    Sets the IMAP authentication method. Valid values are `login' for the usual password-based authentication (the default), `cram-md5', which is a password-based authentication that does not send the password over the network in clear text, and `gssapi' for GSSAPI-based authentication.

imap-auth-user@host
    Sets the IMAP authentication method for a specific account.

imap-cache
    Enables caching of IMAP mailboxes. The value of this variable must point to a directory that is either existent or can be created by nail. All contents of the cache can be deleted by nail at any time; it is not safe to make assumptions about them.

imap-keepalive
    IMAP servers may close the connection after a period of inactivity; the standard requires this to be at least 30 minutes, but practical experience may vary. Setting this variable to a numeric value greater than 0 causes a NOOP command to be sent each value seconds if no other operation is performed.

indentprefix
    String used by the `~m' and `~M' tilde escapes and by the quote option for indenting messages, in place of the normal tab character (^I). Be sure to quote the value if it contains spaces or tabs.

LISTER
    Pathname of the directory lister to use in the folders command when operating on local mailboxes. Default is /bin/ls.

MAIL
    Is used as the user's mailbox, if set. Otherwise, a system-dependent default is used. Can be a protocol:// string (see the folder command for more information).

MAILX_HEAD
    A string to put at the beginning of each new message. The escape sequences `\t' (tabulator) and `\n' (newline) are understood.

MAILX_TAIL
    A string to put at the end of each new message. The escape sequences `\t' (tabulator) and `\n' (newline) are understood.

MBOX
    The name of the mbox file. It can be the name of a folder. The default is `mbox' in the user's home directory.

NAIL_EXTRA_RC
    The name of an optional startup file to be read after ~/.mailrc. This variable is ignored if it is imported from the environment; it has an effect only if it is set in /etc/mail.rc or ~/.mailrc to allow bypassing the configuration with e. g. `MAILRC=/dev/null'. Use this file for nail commands that are not understood by other mailx implementations.

ORGANIZATION
    The value to put into the `Organization:' field of the message header.

PAGER
    Pathname of the program to use in the more command or when crt variable is set. The default paginator pg(1) or, in BSD compatibility mode, more(1) is used if this option is not defined.

password-user@host
    Set the password for user when connecting to host. If no such variable is defined for a host, the user will be asked for a password on standard input. Specifying passwords in a startup file is generally a security risk, the file should be readable by the invoking user only.

pipe-content/subcontent
    When a MIME message part of content/subcontent type is displayed or it is replied to, its text is filtered through the value of this variable interpreted as a shell command. Special care must be taken when using such commands as mail viruses may be distributed by this method; if messages of type application/x-sh were filtered through the shell, for example, a message sender could easily execute arbitrary code on the system nail is running on.

pop3-keepalive
    POP3 servers may close the connection after a period of inactivity; the standard requires this to be at least 10 minutes, but practical experience may vary. Setting this variable to a numeric value greater than 0 causes a NOOP command to be sent each value seconds if no other operation is performed.

prompt
    The string printed when a command is accepted. Defaults to `? ', or to `& ' if the bsdcompat variable is set.

quote
    If set, nail starts a replying message with the original message prefixed by the value of the variable indentprefix. Normally, a heading consisting of `Fromheaderfield wrote:' is printed before the quotation. If the string noheading is assigned to the quote variable, this heading is omitted. If the string headers is assigned, the headers selected by the ignore/retain commands are printed above the message body, thus quote acts like an automatic ~m command then. If the string allheaders is assigned, all headers are printed above the message body, thus quote acts like an automatic ~M command then.

record
    If defined, gives the pathname of the folder used to record all outgoing mail. If not defined, then outgoing mail is not so saved. When saving to this folder fails, the message is not sent but saved to the `dead.letter' file instead.

replyto
    A list of addresses to put into the `Reply-To:' field of the message header. If replying to a message, such addresses are handled as if they were in the alternates list.

screen
    When nail initially prints the message headers, it determines the number to print by looking at the speed of your terminal. The faster your terminal, the more it prints. This option overrides this calculation and specifies how many message headers you want printed. This number is also used for scrolling with the z command.

sendmail
    To use an alternate mail delivery system, set this option to the full pathname of the program to use. This should be used with care.

SHELL
    Pathname of the shell to use in the ! command and the ~! escape. A default shell is used if this option is not defined.

Sign
    A string for use with the ~A command.

sign
    A string for use with the ~a command.

signature
    Must correspond to the name of a readable file if set. The file's content is then appended to each singlepart message and to the first part of each multipart message. Be warned that there is no possibility to edit the signature for an individual message.

smtp
    Normally, nail invokes sendmail(8) directly to transfer messages. If the smtp variable is set, a SMTP connection to the server specified by the value of this variable is used instead. If the SMTP server does not use the standard port, a value of server:port can be given, with port as a name or as a number.

    There are two possible methods to get SSL/TLS encrypted SMTP sessions: First, the STARTTLS command can be used to encrypt a session after it has been initiated, but before any user-related data has been sent; see smtp-use-starttls above. Second, some servers accept sessions that are encrypted from their beginning on. This mode is configured by assigning smtps://server[:port] to the smtp variable.

smtp-auth
    Sets the SMTP authentication method. If set to `login', or if unset and both smtp-auth-user and smtp-auth-password are set, AUTH LOGIN is used. If set to `cram-md5', AUTH CRAM-MD5 is used. Otherwise, no SMTP authentication is performed.

smtp-auth-user@host
    Overrides smtp-auth for specific values of sender addresses, depending on the from variable.

smtp-auth-password
    Sets the global password for SMTP AUTH. Both user and password have to be given for AUTH LOGIN and AUTH CRAM-MD5.

smtp-auth-password-user@host
    Overrides smtp-auth-password for specific values of sender addresses, depending on the from variable.

smtp-auth-user
    Sets the global user name for SMTP AUTH. Both user and password have to be given for AUTH LOGIN and AUTH CRAM-MD5.

smtp-auth-user-user@host
    Overrides smtp-auth-user for specific values of sender addresses, depending on the from variable.

ssl-ca-dir
    Specifies a directory with CA certificates for verification. See SSL_CTX_load_verify_locations(3) for more information.

ssl-ca-file
    Specifies a file with CA certificates for verification. See SSL_CTX_load_verify_locations(3) for more information.

ssl-cert
    Sets the file name for a SSL/TLS client certificate required by some servers.

ssl-cert-user@host
    Sets an account-specific file name for a SSL/TLS client certificate required by some servers. Overrides ssl-cert for the specified account.

ssl-cipher-list
    Specifies a list of ciphers for SSL/TLS connections. See ciphers(1) for more information.

ssl-key
    Sets the file name for the private key of a SSL/TLS client certificate. If unset, the name of the certificate file is used. The file is expected to be in PEM format.

ssl-key-user@host
    Sets an account-specific file name for the private key of a SSL/TLS client certificate. Overrides ssl-key for the specified account.

ssl-method
    Selects a SSL/TLS protocol version; valid values are `ssl2', `ssl3', and `tls1'. If unset, the method is selected automatically, if possible.

ssl-method-user@host
    Overrides ssl-method for a specific account.

ssl-rand-egd
    Gives the pathname to an entropy daemon socket, see RAND_egd(3).

ssl-rand-file
    Gives the pathname to a file with entropy data, see RAND_load_file(3). If the file is a regular file writable by the invoking user, new data is written to it after it has been loaded.

ssl-verify
    Sets the action to be performed if an error occurs during SSL/TLS server certificate validation. Valid values are `strict' (fail and close connection immediately), `ask' (ask whether to continue on standard input), `warn' (print a warning and continue), `ignore' (do not perform validation). The default is `ask'.

ssl-verify-user@host
    Overrides ssl-verify for a specific account.

toplines
    If defined, gives the number of lines of a message to be printed out with the top command; normally, the first five lines are printed.

ttycharset
    The character set of the terminal nail operates on. There is normally no need to set this variable since nail can determine this automatically by looking at the LC_CTYPE locale setting; if this succeeds, the value is assigned at startup and will be displayed by the set command. Note that this is not necessarily a character set name that can be used in Internet messages. If unset, its default is the value of the charset variable.

VISUAL
    Pathname of the text editor to use in the visual command and ~v escape.

ENVIRONMENT VARIABLES
Besides the variables described above, nail uses the following environment strings:

HOME
    The user's home directory.

LANG, LC_ALL, LC_COLLATE, LC_CTYPE, LC_MESSAGES
    See locale(7).

MAILRC
    Is used as startup file instead of ~/.mailrc if set.

NAILRC
    If this variable is set and MAILRC is not set, it is read as startup file.

TMPDIR
    Used as directory for temporary files instead of /tmp, if set.

FILES

~/.mailrc
    File giving initial commands.

/etc/mail.rc
    System wide initialization file.

~/.mime.types
    Personal MIME types.

/etc/mime.types
    System wide MIME types.

EXAMPLES

  IMAP or POP3 client setup
First you need the following data from your ISP: the host name of the IMAP or POP3 server, user name and password for this server, and a notice whether the server uses SSL/TLS encryption. Assuming the host name is `server.myisp.example' and your user name for that server is `mylogin', you can refer to this account using the folder command or -f command line option with
    imaps://mylogin@server.myisp.example
(This string is not necessarily the same as your Internet mail address.) You can replace `imaps://' with `imap://' if the server does not support SSL/TLS, or use `pop3s://' or `pop3://' if the server does not offer IMAP. You should use IMAP if you can, though; first because it requires fewer network operations than POP3 to get the contents of the mailbox and is thus faster; and second because message flags are maintained by the IMAP server, so you can easily distinguish new and old messages each time you connect. Even if the server does not accept IMAPS or POP3S connections, it is possible that it supports the STARTTLS method to make a session SSL/TLS encrypted after the initial connection has been performed, but before authentication begins. The only reliable method to see if this works is to try it; enter one of
    set imap-use-starttls
    set pop3-use-starttls
before you initiate the connection.

As you probably want messages to be deleted from this account after saving them, prefix it with `%:'. The shortcut command can be used to avoid typing that many characters every time you want to connect:
    shortcut myisp %:imaps://mylogin@server.myisp.example
You might want to put this string into a startup file. As the shortcut command is nail-specific and will confuse other mailx implementations, it should not be used in ~/.mailrc, instead, put
    set NAIL_EXTRA_RC=~/.nailrc
in ~/.mailrc and create a file ~/.nailrc containing the shortcut command above. You can then access your remote mailbox by invoking `nail -f myisp' on the command line, or by executing `fi myisp' within nail.

If you want to use more than one IMAP mailbox on a server, or if you want to use the IMAP server for mail storage too, the account command (which is also nail-specific) is more appropriate than the shortcut command. You can put the following in ~/.nailrc:

    account myisp \
        folder=imaps://mylogin@server.myisp.example \
        record=+Sent MBOX=+mbox outfolder

and can then access incoming mail for this account by invoking `nail -A myisp' on the command line, or by executing `ac myisp' within nail. After that, a command like `copy 1 +otherfolder' will refer to otherfolder on the IMAP server. In particular, `fi &' will change to the mbox folder, and `fi +Sent' will show your recorded sent mail, with both folders located on the IMAP server.

Nail will ask you for a password string each time you connect to a remote account. If you can reasonably trust the security of your workstation, you can give this password in the startup file as
    set password-mylogin@server.myisp.example="SECRET"
You should change the permissions of this file to 0600, see chmod(1).

Nail supports different authentication methods for both IMAP and POP3. If Kerberos is used at your location, you can try to activate GSSAPI-based authentication by
    set imap-auth=gssapi
The advantage of this method is that nail does not need to know your password at all, nor needs to send sensitive data over the network. Otherwise, the options
    set imap-auth=cram-md5
    set pop3-use-apop
for IMAP and POP3, respectively, offer authentication methods that avoid to send the password in clear text over the network, which is especially important if SSL/TLS cannot be used. If the server does not offer any of these authentication methods, conventional user/password based authentication must be used. It is sometimes helpful to set the verbose option when authentication problems occur. Nail will display all data sent to the server in clear text on the screen with this option, including passwords. You should thus take care that no unauthorized person can look at your terminal when this option is set.

If you regularly use the same workstation to access IMAP accounts, you can greatly enhance performance by enabling local caching of IMAP messages. For any message that has been fully or partially fetched from the server, a local copy is made and is used when the message is accessed again, so most data is transferred over the network once only. To enable the IMAP cache, select a local directory name and put
    set imap-cache=~/localdirectory
in the startup file. All files within that directory can be overwritten or deleted by nail at any time, so you should not use the directory to store other information.

Once the cache contains some messages, it is not strictly necessary anymore to open a connection to the IMAP server to access them. When nail is invoked with the -D option, or when the disconnected variable is set, only cached data is used for any folder you open. Messages that have not yet been completely cached are not available then, but all other messages can be handled as usual. Changes made to IMAP mailboxes in disconnected mode are committed to the IMAP server next time it is used in online mode. Synchronizing the local status with the status on the server is thus partially within your responsibility; if you forget to initiate a connection to the server again before you leave your location, changes made on one workstation are not available on others. Also if you alter IMAP mailboxes from a workstation while uncommitted changes are still pending on another, the latter data may become invalid. The same might also happen because of internal server status changes. You should thus carefully evaluate this feature in your environment before you rely on it.

Many POP3 servers will close the connection after a short period of inactivity. Use
    set pop3-keepalive=30
to send a keepalive message each 30 seconds. A similar imap-keepalive variable is also available, but since IMAP servers tend to wait much longer until they close an idle connection, it is usually not necessary to activate it.

If you encounter problems connecting to a SSL/TLS server, try the ssl-rand-egd and ssl-rand-file variables (see the OpenSSL FAQ for more information) or specify the protocol version with ssl-method. Contact your ISP if you need a client certificate or if verification of the server certificate fails. If the failed certificate is indeed valid, fetch its CA certificate by executing
    openssl s_client </dev/null -showcerts -connect \
           server.myisp.example:imaps 2>&1 | tee log
(see s_client(1)) and put it into the file specified with ssl-ca-file. The data you need is located at the end of the certificate chain within (and including) the `BEGIN CERTIFICATE' and `END CERTIFICATE' lines. (Note that it is possible to fetch a forged certificate by this method. You can only completely rely on the authenticity of the CA certificate if you fetch it in a way that is trusted by other means, such as by personally receiving the cerfiticate on storage media.)

  Reading HTML mail
You need either the w3m or lynx utility or another command-line web browser that can write plain text to standard output.

    set pipe-text/html="w3m -dump -T text/html"

or

    set pipe-text/html="lynx -dump -force_html /dev/stdin"

will then cause HTML message parts to be converted into a more friendly form.

  Viewing PDF attachments
Most PDF viewers do not accept input directly from a pipe. It is thus necessary to store the attachment in a temporary file, as with

    set pipe-application/pdf="cat >/tmp/nail$$.pdf; \
           acroread /tmp/nail$$.pdf; rm /tmp/nail$$.pdf"

Note that security defects are discovered in PDF viewers from time to time. Automatical command execution like this can compromise your system security, in particular if you stay not always informed about such issues.

SEE ALSO
fmt(1), newaliases(1), openssl(1), pg(1), procmail(1), more(1), vacation(1), ssl(3), aliases(5), locale(7), mailaddr(7), sendmail(8)

NOTES

Variables in the environment passed to nail cannot be unset.

The character set conversion relies heavily on the iconv(3) function. Its functionality differs widely between the various system environments nail runs on.

Nail expects input text to be in Unix format, with lines separated by newline (^J, \n) characters only. Non-Unix text files that use carriage return (^M, \r) characters in addition will be treated as binary data; to send such files as text, strip these characters e. g. by

    tr -d '\015' <input | nail . . .

or fix the tools that generate them.

Limitations with IMAP mailboxes are: It is not possible to edit messages, but it is possible to append them. Thus to edit a message, create a local copy of it, edit it, append it, and delete the original. The line count for the header display is only appropriate if the entire message has been downloaded from the server. The marking of messages as `new' is performed by the IMAP server; use of the exit command instead of quit will not cause it to be reset. Message numbers may change with IMAP every time before the prompt is printed if nail is notified by the server that messages have been deleted by some other client or process. In this case, `Expunged n messages' is printed, and message numbers may have changed.

Limitations with POP3 mailboxes are: It is not possible to edit messages, they can only be copied and deleted. The line count for the header display is only appropriate if the entire message has been downloaded from the server. The status field of a message is maintained by the server between connections; some servers do not update it at all, and with a server that does, the `exit' command will not cause the message status to be reset. The `newmail' command and the `newmail' variable have no effect.

An unencrypted IMAP or POP3 message download can be interrupted from the terminal, but the part that was not downloaded will have to be downloaded before the next command is sent. A SSL/TLS encrypted IMAP or POP3 message download should not be interrupted, as this will very likely cause an error in the SSL transport.

There is no support for SSL/TLS certificate revocation lists (CRLs) yet.

As nail is a mail user agent, it provides only basic SMTP services. If it fails to contact its upstream SMTP server, it will not make further attempts to transfer the message at a later time, and it does not leave other information about this condition than an error message on the terminal and a `dead.letter' file. This is usually not a problem if the SMTP server is located in the same local network as the computer on which nail is run. However, care should be taken when using a remote server of an ISP; it might be better to set up a local SMTP server then which just acts as a proxy.

Nail immediately contacts the SMTP server (or /usr/lib/sendmail) even when operating in disconnected mode. It would not make much sense for nail to defer outgoing mail since SMTP servers usually provide much more elaborated delay handling than nail could perform as a client. Thus the recommended setup for sending mail in disconnected mode is to configure a local SMTP server such that it sends outgoing mail as soon as an external network connection is available again, i.e. to advise it to do that from a network startup script.

Nail is intended to be a MIME-conformant mail user agent, with the following exception: No special handling of `multipart/alternative' messages is performed; all parts with content types of `text' or `message' are shown. This is done because the user should see as much information as possible.

A mail command appeared in Version 1 AT&T Unix. Berkeley Mail was written in 1978 by Kurt Shoens. This man page is derived from from The Mail Reference Manual originally written by Kurt Shoens. Nail enhancements are maintained and documented by Gunnar Ritter.

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology — Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright © 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html . Redistribution of this material is permitted so long as this notice remains intact.