MAILX(1)                   POSIX Programmer's Manual                  MAILX(1)



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NNAAMMEE
       mailx -- process messages

SSYYNNOOPPSSIISS
   SSeenndd MMooddee
           mailx [[-s _s_u_b_j_e_c_t]] _a_d_d_r_e_s_s...

   RReecceeiivvee MMooddee
           mailx -e

           mailx [[-HiNn]] [[-F]] [[-u _u_s_e_r]]

           mailx -f [[-HiNn]] [[-F]] [[_f_i_l_e]]

DDEESSCCRRIIPPTTIIOONN
       The _m_a_i_l_x utility provides a message sending and receiving facility. It
       has two major modes, selected by the options used: Send Mode and
       Receive Mode.

       On systems that do not support the User Portability Utilities option,
       an application using _m_a_i_l_x shall have the ability to send messages in
       an unspecified manner (Send Mode). Unless the first character of one or
       more lines is <tilde> (''~~''), all characters in the input message shall
       appear in the delivered message, but additional characters may be
       inserted in the message before it is retrieved.

       On systems supporting the User Portability Utilities option, mail-
       receiving capabilities and other interactive features, Receive Mode,
       described below, also shall be enabled.

   SSeenndd MMooddee
       Send Mode can be used by applications or users to send messages from
       the text in standard input.

   RReecceeiivvee MMooddee
       Receive Mode is more oriented towards interactive users. Mail can be
       read and sent in this interactive mode.

       When reading mail, _m_a_i_l_x provides commands to facilitate saving,
       deleting, and responding to messages. When sending mail, _m_a_i_l_x allows
       editing, reviewing, and other modification of the message as it is
       entered.

       Incoming mail shall be stored in one or more unspecified locations for
       each user, collectively called the system _m_a_i_l_b_o_x for that user. When
       _m_a_i_l_x is invoked in Receive Mode, the system mailbox shall be the
       default place to find new mail. As messages are read, they shall be
       marked to be moved to a secondary file for storage, unless specific
       action is taken. This secondary file is called the mmbbooxx and is normally
       located in the directory referred to by the _H_O_M_E environment variable
       (see _M_B_O_X in the ENVIRONMENT VARIABLES section for a description of
       this file).  Messages shall remain in this file until explicitly
       removed. When the --ff option is used to read mail messages from
       secondary files, messages shall be retained in those files unless
       specifically removed. All three of these locations--system mailbox,
       mmbbooxx, and secondary file--are referred to in this section as simply
       ``mailboxes'', unless more specific identification is required.

OOPPTTIIOONNSS
       The _m_a_i_l_x utility shall conform to the Base Definitions volume of
       POSIX.1-2017, _S_e_c_t_i_o_n _1_2_._2, _U_t_i_l_i_t_y _S_y_n_t_a_x _G_u_i_d_e_l_i_n_e_s.

       The following options shall be supported. (Only the --ss _s_u_b_j_e_c_t option
       shall be required on all systems. The other options are required only
       on systems supporting the User Portability Utilities option.)

       --ee        Test for the presence of mail in the system mailbox. The
                 _m_a_i_l_x utility shall write nothing and exit with a successful
                 return code if there is mail to read.

       --ff        Read messages from the file named by the _f_i_l_e operand instead
                 of the system mailbox. (See also ffoollddeerr.)  If no _f_i_l_e operand
                 is specified, read messages from mmbbooxx instead of the system
                 mailbox.

       --FF        Record the message in a file named after the first recipient.
                 The name is the login-name portion of the address found first
                 on the TToo:: line in the mail header. Overrides the rreeccoorrdd
                 variable, if set (see _I_n_t_e_r_n_a_l _V_a_r_i_a_b_l_e_s _i_n _m_a_i_l_x).

       --HH        Write a header summary only.

       --ii        Ignore interrupts. (See also iiggnnoorree.)

       --nn        Do not initialize from the system default start-up file. See
                 the EXTENDED DESCRIPTION section.

       --NN        Do not write an initial header summary.

       --ss _s_u_b_j_e_c_t
                 Set the SSuubbjjeecctt header field to _s_u_b_j_e_c_t.  All characters in
                 the _s_u_b_j_e_c_t string shall appear in the delivered message. The
                 results are unspecified if _s_u_b_j_e_c_t is longer than {LINE_MAX}
                 - 10 bytes or contains a <newline>.

       --uu _u_s_e_r   Read the system mailbox of the login name _u_s_e_r.  This shall
                 only be successful if the invoking user has appropriate
                 privileges to read the system mailbox of that user.

OOPPEERRAANNDDSS
       The following operands shall be supported:

       _a_d_d_r_e_s_s   Addressee of message. When --nn is specified and no user start-
                 up files are accessed (see the EXTENDED DESCRIPTION section),
                 the user or application shall ensure this is an address to
                 pass to the mail delivery system. Any system or user start-up
                 files may enable aliases (see aalliiaass under _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x)
                 that may modify the form of _a_d_d_r_e_s_s before it is passed to
                 the mail delivery system.

       _f_i_l_e      A pathname of a file to be read instead of the system mailbox
                 when --ff is specified. The meaning of the _f_i_l_e option-argument
                 shall be affected by the contents of the ffoollddeerr internal
                 variable; see _I_n_t_e_r_n_a_l _V_a_r_i_a_b_l_e_s _i_n _m_a_i_l_x.

SSTTDDIINN
       When _m_a_i_l_x is invoked in Send Mode (the first synopsis line), standard
       input shall be the message to be delivered to the specified addresses.
       When in Receive Mode, user commands shall be accepted from _s_t_d_i_n.  If
       the User Portability Utilities option is not supported, standard input
       lines beginning with a <tilde> (''~~'') character produce unspecified
       results.

       If the User Portability Utilities option is supported, then in both
       Send and Receive Modes, standard input lines beginning with the escape
       character (usually <tilde> (''~~'')) shall affect processing as described
       in _C_o_m_m_a_n_d _E_s_c_a_p_e_s _i_n _m_a_i_l_x.

IINNPPUUTT FFIILLEESS
       When _m_a_i_l_x is used as described by this volume of POSIX.1-2017, the
       _f_i_l_e option-argument (see the --ff option) and the mmbbooxx shall be text
       files containing mail messages, formatted as described in the OUTPUT
       FILES section. The nature of the system mailbox is unspecified; it need
       not be a file.

EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS
       Some of the functionality described in this section shall be provided
       on implementations that support the User Portability Utilities option
       as described in the text, and is not further shaded for this option.

       The following environment variables shall affect the execution of
       _m_a_i_l_x:

       _D_E_A_D      Determine the pathname of the file in which to save partial
                 messages in case of interrupts or delivery errors. The
                 default shall be ddeeaadd..lleetttteerr in the directory named by the
                 _H_O_M_E variable. The behavior of _m_a_i_l_x in saving partial
                 messages is unspecified if the User Portability Utilities
                 option is not supported and _D_E_A_D is not defined with the
                 value //ddeevv//nnuullll.

       _E_D_I_T_O_R    Determine the name of a utility to invoke when the eeddiitt (see
                 _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x) or ~~ee (see _C_o_m_m_a_n_d _E_s_c_a_p_e_s _i_n _m_a_i_l_x)
                 command is used. The default editor is unspecified.  On XSI-
                 conformant systems it is _e_d.  The effects of this variable
                 are unspecified if the User Portability Utilities option is
                 not supported.

       _H_O_M_E      Determine the pathname of the user's home directory.

       _L_A_N_G      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1-2017, _S_e_c_t_i_o_n _8_._2, _I_n_t_e_r_n_a_t_i_o_n_a_l_i_z_a_t_i_o_n
                 _V_a_r_i_a_b_l_e_s for the precedence of internationalization
                 variables used to determine the values of locale categories.)

       _L_C___A_L_L    If set to a non-empty string value, override the values of
                 all the other internationalization variables.

       _L_C___C_T_Y_P_E  Determine the locale for the interpretation of sequences of
                 bytes of text data as characters (for example, single-byte as
                 opposed to multi-byte characters in arguments and input
                 files) and the handling of case-insensitive address and
                 header-field comparisons.

       _L_C___T_I_M_E   This variable may determine the format and contents of the
                 date and time strings written by _m_a_i_l_x.  This volume of
                 POSIX.1-2017 specifies the effects of this variable only for
                 systems supporting the User Portability Utilities option.

       _L_C___M_E_S_S_A_G_E_S
                 Determine the locale that should be used to affect the format
                 and contents of diagnostic messages written to standard error
                 and informative messages written to standard output.

       _L_I_S_T_E_R    Determine a string representing the command for writing the
                 contents of the ffoollddeerr directory to standard output when the
                 ffoollddeerrss command is given (see ffoollddeerrss in _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x).
                 Any string acceptable as a _c_o_m_m_a_n_d___s_t_r_i_n_g operand to the _s_h
                 --cc command shall be valid. If this variable is null or not
                 set, the output command shall be _l_s.  The effects of this
                 variable are unspecified if the User Portability Utilities
                 option is not supported.

       _M_A_I_L_R_C    Determine the pathname of the user start-up file. The default
                 shall be ..mmaaiillrrcc in the directory referred to by the _H_O_M_E
                 environment variable. The behavior of _m_a_i_l_x is unspecified if
                 the User Portability Utilities option is not supported and
                 _M_A_I_L_R_C is not defined with the value //ddeevv//nnuullll.

       _M_B_O_X      Determine a pathname of the file to save messages from the
                 system mailbox that have been read. The eexxiitt command shall
                 override this function, as shall saving the message
                 explicitly in another file. The default shall be mmbbooxx in the
                 directory named by the _H_O_M_E variable. The effects of this
                 variable are unspecified if the User Portability Utilities
                 option is not supported.

       _N_L_S_P_A_T_H   Determine the location of message catalogs for the processing
                 of _L_C___M_E_S_S_A_G_E_S.

       _P_A_G_E_R     Determine a string representing an output filtering or
                 pagination command for writing the output to the terminal.
                 Any string acceptable as a _c_o_m_m_a_n_d___s_t_r_i_n_g operand to the _s_h
                 --cc command shall be valid. When standard output is a terminal
                 device, the message output shall be piped through the command
                 if the _m_a_i_l_x internal variable ccrrtt is set to a value less the
                 number of lines in the message; see _I_n_t_e_r_n_a_l _V_a_r_i_a_b_l_e_s _i_n
                 _m_a_i_l_x.  If the _P_A_G_E_R variable is null or not set, the
                 paginator shall be either _m_o_r_e or another paginator utility
                 documented in the system documentation.  The effects of this
                 variable are unspecified if the User Portability Utilities
                 option is not supported.

       _S_H_E_L_L     Determine the name of a preferred command interpreter. The
                 default shall be _s_h.  The effects of this variable are
                 unspecified if the User Portability Utilities option is not
                 supported.

       _T_E_R_M      If the internal variable ssccrreeeenn is not specified, determine
                 the name of the terminal type to indicate in an unspecified
                 manner the number of lines in a screenful of headers.  If
                 _T_E_R_M is not set or is set to null, an unspecified default
                 terminal type shall be used and the value of a screenful is
                 unspecified. The effects of this variable are unspecified if
                 the User Portability Utilities option is not supported.

       _T_Z        This variable may determine the timezone used to calculate
                 date and time strings written by _m_a_i_l_x.  If _T_Z is unset or
                 null, an unspecified default timezone shall be used.

       _V_I_S_U_A_L    Determine a pathname of a utility to invoke when the vviissuuaall
                 command (see _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x) or ~~vv command-escape (see
                 _C_o_m_m_a_n_d _E_s_c_a_p_e_s _i_n _m_a_i_l_x) is used. If this variable is null
                 or not set, the full-screen editor shall be _v_i.  The effects
                 of this variable are unspecified if the User Portability
                 Utilities option is not supported.

AASSYYNNCCHHRROONNOOUUSS EEVVEENNTTSS
       When _m_a_i_l_x is in Send Mode and standard input is not a terminal, it
       shall take the standard action for all signals.

       In Receive Mode, or in Send Mode when standard input is a terminal, if
       a SIGINT signal is received:

        1. If in command mode, the current command, if there is one, shall be
           aborted, and a command-mode prompt shall be written.

        2. If in input mode:

            a. If iiggnnoorree is set, _m_a_i_l_x shall write ""@@\\nn"", discard the current
               input line, and continue processing, bypassing the message-
               abort mechanism described in item 2b.

            b. If the interrupt was received while sending mail, either when
               in Receive Mode or in Send Mode, a message shall be written,
               and another subsequent interrupt, with no other intervening
               characters typed, shall be required to abort the mail message.
               If in Receive Mode and another interrupt is received, a
               command-mode prompt shall be written.  If in Send Mode and
               another interrupt is received, _m_a_i_l_x shall terminate with a
               non-zero status.

               In both cases listed in item b, if the message is not empty:

                i.  If ssaavvee is enabled and the file named by _D_E_A_D can be
                    created, the message shall be written to the file named by
                    _D_E_A_D.  If the file exists, the message shall be written to
                    replace the contents of the file.

               ii.  If ssaavvee is not enabled, or the file named by _D_E_A_D cannot
                    be created, the message shall not be saved.

       The _m_a_i_l_x utility shall take the standard action for all other signals.

SSTTDDOOUUTT
       In command and input modes, all output, including prompts and messages,
       shall be written to standard output.

SSTTDDEERRRR
       The standard error shall be used only for diagnostic messages.

OOUUTTPPUUTT FFIILLEESS
       Various _m_a_i_l_x commands and command escapes can create or add to files,
       including the mmbbooxx, the dead-letter file, and secondary mailboxes. When
       _m_a_i_l_x is used as described in this volume of POSIX.1-2017, these files
       shall be text files, formatted as follows:

              line beginning with FFrroomm<<ssppaaccee>>
              [[one or more _h_e_a_d_e_r_-_l_i_n_e_s; see _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x]
              _e_m_p_t_y _l_i_n_e
              [[zero or more _b_o_d_y _l_i_n_e_s
              _e_m_p_t_y _l_i_n_e_]
              [[line beginning with FFrroomm<<ssppaaccee>>......]]

       where each message begins with the FFrroomm <<ssppaaccee>> line shown, preceded by
       the beginning of the file or an empty line.  (The FFrroomm <<ssppaaccee>> line is
       considered to be part of the message header, but not one of the header-
       lines referred to in _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x; thus, it shall not be affected
       by the ddiissccaarrdd, iiggnnoorree, or rreettaaiinn commands.) The formats of the
       remainder of the FFrroomm <<ssppaaccee>> line and any additional header lines are
       unspecified, except that none shall be empty. The format of a message
       body line is also unspecified, except that no line following an empty
       line shall start with FFrroomm <<ssppaaccee>>; _m_a_i_l_x shall modify any such user-
       entered message body lines (following an empty line and beginning with
       FFrroomm <<ssppaaccee>>) by adding one or more characters to precede the ''FF''; it
       may add these characters to FFrroomm <<ssppaaccee>> lines that are not preceded by
       an empty line.

       When a message from the system mailbox or entered by the user is not a
       text file, it is implementation-defined how such a message is stored in
       files written by _m_a_i_l_x.

EEXXTTEENNDDEEDD DDEESSCCRRIIPPTTIIOONN
       The functionality in the entire EXTENDED DESCRIPTION section shall be
       provided on implementations supporting the User Portability Utilities
       option.  The functionality described in this section shall be provided
       on implementations that support the User Portability Utilities option
       (and the rest of this section is not further shaded for this option).

       The _m_a_i_l_x utility need not support for all character encodings in all
       circumstances. For example, inter-system mail may be restricted to
       7-bit data by the underlying network, 8-bit data need not be portable
       to non-internationalized systems, and so on. Under these circumstances,
       it is recommended that only characters defined in the ISO/IEC 646:1991
       standard International Reference Version (equivalent to ASCII) 7-bit
       range of characters be used.

       When _m_a_i_l_x is invoked using one of the Receive Mode synopsis forms, it
       shall write a page of header-summary lines (if --NN was not specified and
       there are messages, see below), followed by a prompt indicating that
       _m_a_i_l_x can accept regular commands (see _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x); this is
       termed _c_o_m_m_a_n_d _m_o_d_e.  The page of header-summary lines shall contain
       the first new message if there are new messages, or the first unread
       message if there are unread messages, or the first message. When _m_a_i_l_x
       is invoked using the Send Mode synopsis and standard input is a
       terminal, if no subject is specified on the command line and the aasskkssuubb
       variable is set, a prompt for the subject shall be written. At this
       point, _m_a_i_l_x shall be in input mode. This input mode shall also be
       entered when using one of the Receive Mode synopsis forms and a reply
       or new message is composed using the rreeppllyy, RReeppllyy, ffoolllloowwuupp, FFoolllloowwuupp,
       or mmaaiill commands and standard input is a terminal. When the message is
       typed and the end of the message is encountered, the message shall be
       passed to the mail delivery software. Commands can be entered by
       beginning a line with the escape character (by default, <tilde> (''~~''))
       followed by a single command letter and optional arguments. See
       _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x for a summary of these commands. It is unspecified
       what effect these commands will have if standard input is not a
       terminal when a message is entered using either the Send Mode synopsis,
       or the Read Mode commands rreeppllyy, RReeppllyy, ffoolllloowwuupp, FFoolllloowwuupp, or mmaaiill.

       NNoottee::     For notational convenience, this section uses the default
                 escape character, <tilde>, in all references and examples.

       At any time, the behavior of _m_a_i_l_x shall be governed by a set of
       environmental and internal variables.  These are flags and valued
       parameters that can be set and cleared via the _m_a_i_l_x sseett and uunnsseett
       commands.

       Regular commands are of the form:


           [[_c_o_m_m_a_n_d]] [[_m_s_g_l_i_s_t]] [[_a_r_g_u_m_e_n_t ...]]

       If no _c_o_m_m_a_n_d is specified in command mode, nneexxtt shall be assumed. In
       input mode, commands shall be recognized by the escape character, and
       lines not treated as commands shall be taken as input for the message.

       In command mode, each message shall be assigned a sequential number,
       starting with 1.

       All messages have a state that shall affect how they are displayed in
       the header summary and how they are retained or deleted upon
       termination of _m_a_i_l_x.  There is at any time the notion of a _c_u_r_r_e_n_t
       message, which shall be marked by a ''>>'' at the beginning of a line in
       the header summary. When _m_a_i_l_x is invoked using one of the Receive Mode
       synopsis forms, the current message shall be the first new message, if
       there is a new message, or the first unread message if there is an
       unread message, or the first message if there are any messages, or
       unspecified if there are no messages in the mailbox. Each command that
       takes an optional list of messages (_m_s_g_l_i_s_t) or an optional single
       message (_m_e_s_s_a_g_e) on which to operate shall leave the current message
       set to the highest-numbered message of the messages specified, unless
       the command deletes messages, in which case the current message shall
       be set to the first undeleted message (that is, a message not in the
       deleted state) after the highest-numbered message deleted by the
       command, if one exists, or the first undeleted message before the
       highest-numbered message deleted by the command, if one exists, or to
       an unspecified value if there are no remaining undeleted messages. All
       messages shall be in one of the following states:

       _n_e_w       The message is present in the system mailbox and has not been
                 viewed by the user or moved to any other state. Messages in
                 state _n_e_w when _m_a_i_l_x quits shall be retained in the system
                 mailbox.

       _u_n_r_e_a_d    The message has been present in the system mailbox for more
                 than one invocation of _m_a_i_l_x and has not been viewed by the
                 user or moved to any other state.  Messages in state _u_n_r_e_a_d
                 when _m_a_i_l_x quits shall be retained in the system mailbox.

       _r_e_a_d      The message has been processed by one of the following
                 commands: ~~ff, ~~mm, ~~FF, ~~MM, ccooppyy, mmbbooxx, nneexxtt, ppiippee, pprriinntt,
                 PPrriinntt, ttoopp, ttyyppee, TTyyppee, uunnddeelleettee.  The ddeelleettee, ddpp, and ddtt
                 commands may also cause the next message to be marked as
                 _r_e_a_d, depending on the value of the aauuttoopprriinntt variable.
                 Messages that are in the system mailbox and in state _r_e_a_d
                 when _m_a_i_l_x quits shall be saved in the mmbbooxx, unless the
                 internal variable hhoolldd was set. Messages that are in the mmbbooxx
                 or in a secondary mailbox and in state _r_e_a_d when _m_a_i_l_x quits
                 shall be retained in their current location.

       _d_e_l_e_t_e_d   The message has been processed by one of the following
                 commands: ddeelleettee, ddpp, ddtt.  Messages in state _d_e_l_e_t_e_d when
                 _m_a_i_l_x quits shall be deleted. Deleted messages shall be
                 ignored until _m_a_i_l_x quits or changes mailboxes or they are
                 specified to the undelete command; for example, the message
                 specification /_s_t_r_i_n_g shall only search the subject lines of
                 messages that have not yet been deleted, unless the command
                 operating on the list of messages is uunnddeelleettee.  No deleted
                 message or deleted message header shall be displayed by any
                 _m_a_i_l_x command other than uunnddeelleettee.

       _p_r_e_s_e_r_v_e_d The message has been processed by a pprreesseerrvvee command. When
                 _m_a_i_l_x quits, the message shall be retained in its current
                 location.

       _s_a_v_e_d     The message has been processed by one of the following
                 commands: ssaavvee or wwrriittee.  If the current mailbox is the
                 system mailbox, and the internal variable kkeeeeppssaavvee is set,
                 messages in the state saved shall be saved to the file
                 designated by the _M_B_O_X variable (see the ENVIRONMENT
                 VARIABLES section). If the current mailbox is the system
                 mailbox, messages in the state _s_a_v_e_d shall be deleted from
                 the current mailbox, when the qquuiitt or ffiillee command is used to
                 exit the current mailbox.

       The header-summary line for each message shall indicate the state of
       the message.

       Many commands take an optional list of messages (_m_s_g_l_i_s_t) on which to
       operate, which defaults to the current message. A _m_s_g_l_i_s_t is a list of
       message specifications separated by <blank> characters, which can
       include:

       n       Message number _n.

       +       The next undeleted message, or the next deleted message for the
               uunnddeelleettee command.

       -       The next previous undeleted message, or the next previous
               deleted message for the uunnddeelleettee command.

       .       The current message.

       ^       The first undeleted message, or the first deleted message for
               the uunnddeelleettee command.

       $       The last message.

       *       All messages.

       n-m     An inclusive range of message numbers.

       _a_d_d_r_e_s_s All messages from _a_d_d_r_e_s_s; any address as shown in a header
               summary shall be matchable in this form.

       /_s_t_r_i_n_g All messages with _s_t_r_i_n_g in the subject line (case ignored).

       :c      All messages of type _c, where _c shall be one of:

               d     Deleted messages.

               n     New messages.

               o     Old messages (any not in state _r_e_a_d or _n_e_w).

               r     Read messages.

               u     Unread messages.

       Other commands take an optional message (_m_e_s_s_a_g_e) on which to operate,
       which defaults to the current message. All of the forms allowed for
       _m_s_g_l_i_s_t are also allowed for _m_e_s_s_a_g_e, but if more than one message is
       specified, only the first shall be operated on.

       Other arguments are usually arbitrary strings whose usage depends on
       the command involved.

   SSttaarrtt--UUpp iinn mmaaiillxx
       At start-up time, _m_a_i_l_x shall take the following steps in sequence:

        1. Establish all variables at their stated default values.

        2. Process command line options, overriding corresponding default
           values.

        3. Import any of the _D_E_A_D, _E_D_I_T_O_R, _M_B_O_X, _L_I_S_T_E_R, _P_A_G_E_R, _S_H_E_L_L, or
           _V_I_S_U_A_L variables that are present in the environment, overriding
           the corresponding default values.

        4. Read _m_a_i_l_x commands from an unspecified system start-up file,
           unless the --nn option is given, to initialize any internal _m_a_i_l_x
           variables and aliases.

        5. Process the user start-up file of _m_a_i_l_x commands named in the user
           _M_A_I_L_R_C variable.

       Most regular _m_a_i_l_x commands are valid inside start-up files, the most
       common use being to set up initial display options and alias lists. The
       following commands shall be invalid in a start-up file: !!, eeddiitt, hhoolldd,
       mmaaiill, pprreesseerrvvee, rreeppllyy, RReeppllyy, sshheellll, vviissuuaall, CCooppyy, ffoolllloowwuupp, and
       FFoolllloowwuupp.  Any errors in a start-up file shall either cause _m_a_i_l_x to
       terminate with a diagnostic message and a non-zero status or to
       continue after writing a diagnostic message, ignoring the remainder of
       the lines in the file.

       A blank line in a start-up file shall be ignored.

   IInntteerrnnaall VVaarriiaabblleess iinn mmaaiillxx
       The following variables are internal _m_a_i_l_x variables. Each internal
       variable can be set via the _m_a_i_l_x sseett command at any time. The uunnsseett
       and sseett nnoo _n_a_m_e commands can be used to erase variables.

       In the following list, variables shown as:


           variable

       represent Boolean values. Variables shown as:


           variable=_v_a_l_u_e

       shall be assigned string or numeric values. For string values, the
       rules in _C_o_m_m_a_n_d_s _i_n _m_a_i_l_x concerning filenames and quoting shall also
       apply.

       The defaults specified here may be changed by the unspecified system
       start-up file unless the user specifies the --nn option.

       aallllnneett    All network names whose login name components match shall be
                 treated as identical. This shall cause the _m_s_g_l_i_s_t message
                 specifications to behave similarly. The default shall be
                 nnooaallllnneett.  See also the aalltteerrnnaatteess command and the mmeettoooo
                 variable.

       aappppeenndd    Append messages to the end of the mmbbooxx file upon termination
                 instead of placing them at the beginning. The default shall
                 be nnooaappppeenndd.  This variable shall not affect the ssaavvee command
                 when saving to mmbbooxx.

       aasskk, aasskkssuubb
                 Prompt for a subject line on outgoing mail if one is not
                 specified on the command line with the --ss option. The aasskk and
                 aasskkssuubb forms are synonyms; the system shall refer to aasskkssuubb
                 and nnooaasskkssuubb in its messages, but shall accept aasskk and nnooaasskk
                 as user input to mean aasskkssuubb and nnooaasskkssuubb.  It shall not be
                 possible to set both aasskk and nnooaasskkssuubb, or nnooaasskk and aasskkssuubb.
                 The default shall be aasskkssuubb, but no prompting shall be done
                 if standard input is not a terminal.

       aasskkbbcccc    Prompt for the blind copy list. The default shall be
                 nnooaasskkbbcccc.

       aasskkcccc     Prompt for the copy list. The default shall be nnooaasskkcccc.

       aauuttoopprriinntt Enable automatic writing of messages after ddeelleettee and
                 uunnddeelleettee commands. The default shall be nnooaauuttoopprriinntt.

       bbaanngg      Enable the special-case treatment of <exclamation-mark>
                 characters (''!!'')  in escape command lines; see the eessccaappee
                 command and _C_o_m_m_a_n_d _E_s_c_a_p_e_s _i_n _m_a_i_l_x.  The default shall be
                 nnoobbaanngg, disabling the expansion of ''!!''  in the _c_o_m_m_a_n_d
                 argument to the ~~!!  command and the ~~<<!!_c_o_m_m_a_n_d escape.

       ccmmdd=_c_o_m_m_a_n_d
                 Set the default command to be invoked by the ppiippee command.
                 The default shall be nnooccmmdd.

       ccrrtt=_n_u_m_b_e_r
                 Pipe messages having more than _n_u_m_b_e_r lines through the
                 command specified by the value of the _P_A_G_E_R variable. The
                 default shall be nnooccrrtt.  If it is set to null, the value used
                 is implementation-defined.

       ddeebbuugg     Enable verbose diagnostics for debugging. Messages are not
                 delivered.  The default shall be nnooddeebbuugg.

       ddoott       When ddoott is set, a <period> on a line by itself during
                 message input from a terminal shall also signify end-of-file
                 (in addition to normal end-of-file). The default shall be
                 nnooddoott.  If iiggnnoorreeeeooff is set (see below), a setting of nnooddoott
                 shall be ignored and the <period> is the only method to
                 terminate input mode.

       eessccaappee=_c  Set the command escape character to be the character ''cc''.  By
                 default, the command escape character shall be <tilde>.  If
                 eessccaappee is unset, <tilde> shall be used; if it is set to null,
                 command escaping shall be disabled.

       fflliipprr     Reverse the meanings of the RR and rr commands. The default
                 shall be nnoofflliipprr.

       ffoollddeerr=_d_i_r_e_c_t_o_r_y
                 The default directory for saving mail files. User-specified
                 filenames beginning with a <plus-sign> (''++'') shall be
                 expanded by preceding the filename with this directory name
                 to obtain the real pathname. If _d_i_r_e_c_t_o_r_y does not start with
                 a <slash> (''//''), the contents of _H_O_M_E shall be prefixed to
                 it. The default shall be nnooffoollddeerr.  If ffoollddeerr is unset or set
                 to null, user-specified filenames beginning with ''++'' shall
                 refer to files in the current directory that begin with the
                 literal ''++'' character. See also oouuttffoollddeerr below. The ffoollddeerr
                 value need not affect the processing of the files named in
                 _M_B_O_X and _D_E_A_D.

       hheeaaddeerr    Enable writing of the header summary when entering _m_a_i_l_x in
                 Receive Mode. The default shall be hheeaaddeerr.

       hhoolldd      Preserve all messages that are read in the system mailbox
                 instead of putting them in the mmbbooxx save file. The default
                 shall be nnoohhoolldd.

       iiggnnoorree    Ignore interrupts while entering messages. The default shall
                 be nnooiiggnnoorree.

       iiggnnoorreeeeooff Ignore normal end-of-file during message input. Input can be
                 terminated only by entering a <period> (''..'')  on a line by
                 itself or by the ~~..  command escape. The default shall be
                 nnooiiggnnoorreeeeooff.  See also ddoott above.

       iinnddeennttpprreeffiixx=_s_t_r_i_n_g
                 A string that shall be added as a prefix to each line that is
                 inserted into the message by the ~~mm command escape. This
                 variable shall default to one <tab>.

       kkeeeepp      When a system mailbox, secondary mailbox, or mmbbooxx is empty,
                 truncate it to zero length instead of removing it. The
                 default shall be nnookkeeeepp.

       kkeeeeppssaavvee  Keep the messages that have been saved from the system
                 mailbox into other files in the file designated by the
                 variable _M_B_O_X, instead of deleting them. The default shall be
                 nnookkeeeeppssaavvee.

       mmeettoooo     Suppress the deletion of the login name of the user from the
                 recipient list when replying to a message or sending to a
                 group. The default shall be nnoommeettoooo.

       oonneehhoopp    When responding to a message that was originally sent to
                 several recipients, the other recipient addresses are
                 normally forced to be relative to the originating author's
                 machine for the response. This flag disables alteration of
                 the recipients' addresses, improving efficiency in a network
                 where all machines can send directly to all other machines
                 (that is, one hop away). The default shall be nnoooonneehhoopp.

       oouuttffoollddeerr Cause the files used to record outgoing messages to be
                 located in the directory specified by the ffoollddeerr variable
                 unless the pathname is absolute. The default shall be
                 nnoooouuttffoollddeerr.  See the rreeccoorrdd variable.

       ppaaggee      Insert a <form-feed> after each message sent through the pipe
                 created by the ppiippee command. The default shall be nnooppaaggee.

       pprroommpptt=_s_t_r_i_n_g
                 Set the command-mode prompt to _s_t_r_i_n_g.  If _s_t_r_i_n_g is null or
                 if nnoopprroommpptt is set, no prompting shall occur. The default
                 shall be to prompt with the string ""?? "".

       qquuiieett     Refrain from writing the opening message and version when
                 entering _m_a_i_l_x.  The default shall be nnooqquuiieett.

       rreeccoorrdd=_f_i_l_e
                 Record all outgoing mail in the file with the pathname _f_i_l_e.
                 The default shall be nnoorreeccoorrdd.  See also oouuttffoollddeerr above.

       ssaavvee      Enable saving of messages in the dead-letter file on
                 interrupt or delivery error. See the variable _D_E_A_D for the
                 location of the dead-letter file. The default shall be ssaavvee.

       ssccrreeeenn=_n_u_m_b_e_r
                 Set the number of lines in a screenful of headers for the
                 hheeaaddeerrss and zz commands. If ssccrreeeenn is not specified, a value
                 based on the terminal type identified by the _T_E_R_M environment
                 variable, the window size, the baud rate, or some combination
                 of these shall be used.

       sseennddwwaaiitt  Wait for the background mailer to finish before returning.
                 The default shall be nnoosseennddwwaaiitt.

       sshhoowwttoo    When the sender of the message was the user who is invoking
                 _m_a_i_l_x, write the information from the TToo:: line instead of the
                 FFrroomm:: line in the header summary. The default shall be
                 nnoosshhoowwttoo.

       ssiiggnn=_s_t_r_i_n_g
                 Set the variable inserted into the text of a message when the
                 ~~aa command escape is given. The default shall be nnoossiiggnn.  The
                 character sequences ''\\tt'' and ''\\nn'' shall be recognized in the
                 variable as <tab> and <newline> characters, respectively.
                 (See also ~~ii in _C_o_m_m_a_n_d _E_s_c_a_p_e_s _i_n _m_a_i_l_x.)

       SSiiggnn=_s_t_r_i_n_g
                 Set the variable inserted into the text of a message when the
                 ~~AA command escape is given. The default shall be nnooSSiiggnn.  The
                 character sequences ''\\tt'' and ''\\nn'' shall be recognized in the
                 variable as <tab> and <newline> characters, respectively.

       ttoopplliinneess=_n_u_m_b_e_r
                 Set the number of lines of the message to write with the ttoopp
                 command. The default shall be 5.

   CCoommmmaannddss iinn mmaaiillxx
       The following _m_a_i_l_x commands shall be provided. In the following list,
       header refers to lines from the message header, as shown in the OUTPUT
       FILES section.  Header-line refers to lines within the header that
       begin with one or more non-white-space characters, immediately followed
       by a <colon> and white space and continuing until the next line
       beginning with a non-white-space character or an empty line. Header-
       field refers to the portion of a header line prior to the first <colon>
       in that line.

       For each of the commands listed below, the command can be entered as
       the abbreviation (those characters in the Synopsis command word
       preceding the ''[[''), the full command (all characters shown for the
       command word, omitting the ''[['' and '']]''), or any truncation of the full
       command down to the abbreviation. For example, the eexxiitt command (shown
       as eexx[[iitt]] in the Synopsis) can be entered as eexx, eexxii, or eexxiitt.

       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 shall be treated literally
           as part of the argument. A double-quote shall be treated literally
           within single-quotes and _v_i_c_e _v_e_r_s_a. These special properties of
           the <quotation-mark> characters shall occur only when they are
           paired at the beginning and end of the argument.

        *  A <backslash> outside of the enclosing quotes shall be discarded
           and the following character treated literally as part of the
           argument.

        *  An unquoted <backslash> at the end of a command line shall be
           discarded and the next line shall continue the command.

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

        *  If the filename begins with an unquoted <plus-sign>, and the ffoollddeerr
           variable is defined (see the ffoollddeerr variable), the <plus-sign>
           shall be replaced by the value of the ffoollddeerr variable followed by a
           <slash>.  If the ffoollddeerr variable is unset or is set to null, the
           filename shall be unchanged.

        *  Shell word expansions shall be applied to the filename (see _S_e_c_t_i_o_n
           _2_._6, _W_o_r_d _E_x_p_a_n_s_i_o_n_s).  If more than a single pathname results from
           this expansion and the command is expecting one file, the effects
           are unspecified.

   DDeeccllaarree AAlliiaasseess
       _S_y_n_o_p_s_i_s:

                     a[[lias]] [[_a_l_i_a_s [[_a_d_d_r_e_s_s...]]]]
                     g[[roup]] [[_a_l_i_a_s [[_a_d_d_r_e_s_s...]]]]

       Add the given addresses to the alias specified by _a_l_i_a_s.  The names
       shall be substituted when _a_l_i_a_s is used as a recipient address
       specified by the user in an outgoing message (that is, other recipients
       addressed indirectly through the rreeppllyy command shall not be substituted
       in this manner). Mail address alias substitution shall apply only when
       the alias string is used as a full address; for example, when hhlljj is an
       alias, _h_l_j_@_p_o_s_i_x_._c_o_m does not trigger the alias substitution. If no
       arguments are given, write a listing of the current aliases to standard
       output. If only an _a_l_i_a_s argument is given, write a listing of the
       specified alias to standard output. These listings need not reflect the
       same order of addresses that were entered.

   DDeeccllaarree AAlltteerrnnaattiivveess
       _S_y_n_o_p_s_i_s:

                     alt[[ernates]] _n_a_m_e...

       (See also the mmeettoooo variable.) Declare a list of alternative names for
       the user's login.  When responding to a message, these names shall be
       removed from the list of recipients for the response. The comparison of
       names shall be in a case-insensitive manner. With no arguments,
       aalltteerrnnaatteess shall write the current list of alternative names.

   CChhaannggee CCuurrrreenntt DDiirreeccttoorryy
       _S_y_n_o_p_s_i_s:

                     cd [[_d_i_r_e_c_t_o_r_y]]
                     ch[[dir]] [[_d_i_r_e_c_t_o_r_y]]

       Change directory. If _d_i_r_e_c_t_o_r_y is not specified, the contents of _H_O_M_E
       shall be used.

   CCooppyy MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     c[[opy]] [[_f_i_l_e]]
                     c[[opy]] [[_m_s_g_l_i_s_t]] _f_i_l_e
                     C[[opy]] [[_m_s_g_l_i_s_t]]

       Copy messages to the file named by the pathname _f_i_l_e without marking
       the messages as saved. Otherwise, it shall be equivalent to the ssaavvee
       command.

       In the capitalized form, save the specified messages in a file whose
       name is derived from the author of the message to be saved, without
       marking the messages as saved. Otherwise, it shall be equivalent to the
       SSaavvee command.

   DDeelleettee MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     d[[elete]] [[_m_s_g_l_i_s_t]]

       Mark messages for deletion from the mailbox. The deletions shall not
       occur until _m_a_i_l_x quits (see the qquuiitt command) or changes mailboxes
       (see the ffoollddeerr command). If aauuttoopprriinntt is set and there are messages
       remaining after the ddeelleettee command, the current message shall be
       written as described for the pprriinntt command (see the pprriinntt command);
       otherwise, the _m_a_i_l_x prompt shall be written.

   DDiissccaarrdd HHeeaaddeerr FFiieellddss
       _S_y_n_o_p_s_i_s:

                     di[[scard]] [[_h_e_a_d_e_r_-_f_i_e_l_d...]]
                     ig[[nore]] [[_h_e_a_d_e_r_-_f_i_e_l_d...]]

       Suppress the specified header fields when writing messages. Specified
       _h_e_a_d_e_r_-_f_i_e_l_d_s shall be added to the list of suppressed header fields.
       Examples of header fields to ignore are ssttaattuuss and cccc.  The fields
       shall be included when the message is saved. The PPrriinntt and TTyyppee
       commands shall override this command. The comparison of header fields
       shall be in a case-insensitive manner. If no arguments are specified,
       write a list of the currently suppressed header fields to standard
       output; the listing need not reflect the same order of header fields
       that were entered.

       If both rreettaaiinn and ddiissccaarrdd commands are given, ddiissccaarrdd commands shall
       be ignored.

   DDeelleettee MMeessssaaggeess aanndd DDiissppllaayy
       _S_y_n_o_p_s_i_s:

                     dp [[_m_s_g_l_i_s_t]]
                     dt [[_m_s_g_l_i_s_t]]

       Delete the specified messages as described for the ddeelleettee command,
       except that the aauuttoopprriinntt variable shall have no effect, and the
       current message shall be written only if it was set to a message after
       the last message deleted by the command. Otherwise, an informational
       message to the effect that there are no further messages in the mailbox
       shall be written, followed by the _m_a_i_l_x prompt.

   EEcchhoo aa SSttrriinngg
       _S_y_n_o_p_s_i_s:

                     ec[[ho]] _s_t_r_i_n_g ...

       Echo the given strings, equivalent to the shell _e_c_h_o utility.

   EEddiitt MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     e[[dit]] [[_m_s_g_l_i_s_t]]

       Edit the given messages. The messages shall be placed in a temporary
       file and the utility named by the _E_D_I_T_O_R variable is invoked to edit
       each file in sequence. The default _E_D_I_T_O_R is unspecified.

       The eeddiitt command does not modify the contents of those messages in the
       mailbox.

   EExxiitt
       _S_y_n_o_p_s_i_s:

                     ex[[it]]
                     x[[it]]

       Exit from _m_a_i_l_x without changing the mailbox. No messages shall be
       saved in the mmbbooxx (see also qquuiitt).

   CChhaannggee FFoollddeerr
       _S_y_n_o_p_s_i_s:

                     fi[[le]] [[_f_i_l_e]]
                     fold[[er]] [[_f_i_l_e]]

       Quit (see the qquuiitt command) from the current file of messages and read
       in the file named by the pathname _f_i_l_e.  If no argument is given, the
       name and status of the current mailbox shall be written.

       Several unquoted special characters shall be recognized when used as
       _f_i_l_e names, with the following substitutions:

       %       The system mailbox for the invoking user.

       %_u_s_e_r   The system mailbox for _u_s_e_r.

       #       The previous file.

       &       The current mmbbooxx.

       +_f_i_l_e   The named file in the ffoollddeerr directory. (See the ffoollddeerr
               variable.)

       The default file shall be the current mailbox.

   DDiissppllaayy LLiisstt ooff FFoollddeerrss
       _S_y_n_o_p_s_i_s:

                     folders

       Write the names of the files in the directory set by the ffoollddeerr
       variable. The command specified by the _L_I_S_T_E_R environment variable
       shall be used (see the ENVIRONMENT VARIABLES section).

   FFoollllooww UUpp SSppeecciiffiieedd MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     fo[[llowup]] [[_m_e_s_s_a_g_e]]
                     F[[ollowup]] [[_m_s_g_l_i_s_t]]

       In the lowercase form, respond to a message, recording the response in
       a file whose name is derived from the author of the message. See also
       the ssaavvee and ccooppyy commands and oouuttffoollddeerr.

       In the capitalized form, respond to the first message in the _m_s_g_l_i_s_t,
       sending the message to the author of each message in the _m_s_g_l_i_s_t.  The
       subject line shall be taken from the first message and the response
       shall be recorded in a file whose name is derived from the author of
       the first message. See also the SSaavvee and CCooppyy commands and oouuttffoollddeerr.

       Both forms shall override the rreeccoorrdd variable, if set.

   DDiissppllaayy HHeeaaddeerr SSuummmmaarryy ffoorr SSppeecciiffiieedd MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     f[[rom]] [[_m_s_g_l_i_s_t]]

       Write the header summary for the specified messages.

   DDiissppllaayy HHeeaaddeerr SSuummmmaarryy
       _S_y_n_o_p_s_i_s:

                     h[[eaders]] [[_m_e_s_s_a_g_e]]

       Write the page of headers that includes the message specified. If the
       _m_e_s_s_a_g_e argument is not specified, the current message shall not
       change.  However, if the _m_e_s_s_a_g_e argument is specified, the current
       message shall become the message that appears at the top of the page of
       headers that includes the message specified. The ssccrreeeenn variable sets
       the number of headers per page. See also the zz command.

   HHeellpp
       _S_y_n_o_p_s_i_s:

                     hel[[p]]
                     ?

       Write a summary of commands.

   HHoolldd MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     ho[[ld]] [[_m_s_g_l_i_s_t]]
                     pre[[serve]] [[_m_s_g_l_i_s_t]]

       Mark the messages in _m_s_g_l_i_s_t to be retained in the mailbox when _m_a_i_l_x
       terminates. This shall override any commands that might previously have
       marked the messages to be deleted. During the current invocation of
       _m_a_i_l_x, only the ddeelleettee, ddpp, or ddtt commands shall remove the _p_r_e_s_e_r_v_e
       marking of a message.

   EExxeeccuuttee CCoommmmaannddss CCoonnddiittiioonnaallllyy
       _S_y_n_o_p_s_i_s:

                     i[[f]] s|r
                     _m_a_i_l_-_c_o_m_m_a_n_ds
                     el[[se]]
                     _m_a_i_l_-_c_o_m_m_a_n_ds
                     en[[dif]]

       Execute commands conditionally, where iiff ss executes the following _m_a_i_l_-
       _c_o_m_m_a_n_ds, up to an eellssee or eennddiiff, if the program is in Send Mode, and
       iiff rr shall cause the _m_a_i_l_-_c_o_m_m_a_n_ds to be executed only in Receive Mode.

   LLiisstt AAvvaaiillaabbllee CCoommmmaannddss
       _S_y_n_o_p_s_i_s:

                     l[[ist]]

       Write a list of all commands available. No explanation shall be given.

   MMaaiill aa MMeessssaaggee
       _S_y_n_o_p_s_i_s:

                     m[[ail]] _a_d_d_r_e_s_s...

       Mail a message to the specified addresses or aliases.

   DDiirreecctt MMeessssaaggeess ttoo mmbbooxx
       _S_y_n_o_p_s_i_s:

                     mb[[ox]] [[_m_s_g_l_i_s_t]]

       Arrange for the given messages to end up in the mmbbooxx save file when
       _m_a_i_l_x terminates normally. See _M_B_O_X.  See also the eexxiitt and qquuiitt
       commands.

   PPrroocceessss NNeexxtt SSppeecciiffiieedd MMeessssaaggee
       _S_y_n_o_p_s_i_s:

                     n[[ext]] [[_m_e_s_s_a_g_e]]

       If the current message has not been written (for example, by the pprriinntt
       command) since _m_a_i_l_x started or since any other message was the current
       message, behave as if the pprriinntt command was entered. Otherwise, if
       there is an undeleted message after the current message, make it the
       current message and behave as if the pprriinntt command was entered.
       Otherwise, an informational message to the effect that there are no
       further messages in the mailbox shall be written, followed by the _m_a_i_l_x
       prompt. Should the current message location be the result of an
       immediately preceding hhoolldd, mmbbooxx, pprreesseerrvvee, or ttoouucchh command, nneexxtt will
       act as if the current message has already been written.

   PPiippee MMeessssaaggee
       _S_y_n_o_p_s_i_s:

                     pi[[pe]] [[[[_m_s_g_l_i_s_t]] _c_o_m_m_a_n_d]]
                     | [[[[_m_s_g_l_i_s_t]] _c_o_m_m_a_n_d]]

       Pipe the messages through the given _c_o_m_m_a_n_d by invoking the command
       interpreter specified by _S_H_E_L_L with two arguments: --cc and _c_o_m_m_a_n_d.
       (See also _s_h --cc.)  The application shall ensure that the command is
       given as a single argument. Quoting, described previously, can be used
       to accomplish this. If no arguments are given, the current message
       shall be piped through the command specified by the value of the ccmmdd
       variable. If the ppaaggee variable is set, a <form-feed> shall be inserted
       after each message.

   DDiissppllaayy MMeessssaaggee wwiitthh HHeeaaddeerrss
       _S_y_n_o_p_s_i_s:

                     P[[rint]] [[_m_s_g_l_i_s_t]]
                     T[[ype]] [[_m_s_g_l_i_s_t]]

       Write the specified messages, including all header lines, to standard
       output. Override suppression of lines by the ddiissccaarrdd, iiggnnoorree, and
       rreettaaiinn commands. If ccrrtt is set, the messages longer than the number of
       lines specified by the ccrrtt variable shall be paged through the command
       specified by the _P_A_G_E_R environment variable.

   DDiissppllaayy MMeessssaaggee
       _S_y_n_o_p_s_i_s:

                     p[[rint]] [[_m_s_g_l_i_s_t]]
                     t[[ype]] [[_m_s_g_l_i_s_t]]

       Write the specified messages to standard output. If ccrrtt is set, the
       messages longer than the number of lines specified by the ccrrtt variable
       shall be paged through the command specified by the _P_A_G_E_R environment
       variable.

   QQuuiitt
       _S_y_n_o_p_s_i_s:

                     q[[uit]]
                     _e_n_d_-_o_f_-_f_i_l_e

       Terminate _m_a_i_l_x, storing messages that were read in mmbbooxx (if the
       current mailbox is the system mailbox and unless hhoolldd is set), deleting
       messages that have been explicitly saved (unless kkeeeeppssaavvee is set),
       discarding messages that have been deleted, and saving all remaining
       messages in the mailbox.

   RReeppllyy ttoo aa MMeessssaaggee LLiisstt
       _S_y_n_o_p_s_i_s:

                     R[[eply]] [[_m_s_g_l_i_s_t]]
                     R[[espond]] [[_m_s_g_l_i_s_t]]

       Mail a reply message to the sender of each message in the _m_s_g_l_i_s_t.  The
       subject line shall be formed by concatenating RRee::<space> (unless it
       already begins with that string) and the subject from the first
       message. If rreeccoorrdd is set to a filename, the response shall be saved at
       the end of that file.

       See also the fflliipprr variable.

   RReeppllyy ttoo aa MMeessssaaggee
       _S_y_n_o_p_s_i_s:

                     r[[eply]] [[_m_e_s_s_a_g_e]]
                     r[[espond]] [[_m_e_s_s_a_g_e]]

       Mail a reply message to all recipients included in the header of the
       message. The subject line shall be formed by concatenating RRee::<space>
       (unless it already begins with that string) and the subject from the
       message. If rreeccoorrdd is set to a filename, the response shall be saved at
       the end of that file.

       See also the fflliipprr variable.

   RReettaaiinn HHeeaaddeerr FFiieellddss
       _S_y_n_o_p_s_i_s:

                     ret[[ain]] [[_h_e_a_d_e_r_-_f_i_e_l_d...]]

       Retain the specified header fields when writing messages. This command
       shall override all ddiissccaarrdd and iiggnnoorree commands. The comparison of
       header fields shall be in a case-insensitive manner. If no arguments
       are specified, write a list of the currently retained header fields to
       standard output; the listing need not reflect the same order of header
       fields that were entered.

   SSaavvee MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     s[[ave]] [[_f_i_l_e]]
                     s[[ave]] [[_m_s_g_l_i_s_t]] _f_i_l_e
                     S[[ave]] [[_m_s_g_l_i_s_t]]

       Save the specified messages in the file named by the pathname _f_i_l_e, or
       the mmbbooxx if the _f_i_l_e argument is omitted. The file shall be created if
       it does not exist; otherwise, the messages shall be appended to the
       file. The message shall be put in the state _s_a_v_e_d, and shall behave as
       specified in the description of the _s_a_v_e_d state when the current
       mailbox is exited by the qquuiitt or ffiillee command.

       In the capitalized form, save the specified messages in a file whose
       name is derived from the author of the first message. The name of the
       file shall be taken to be the author's name with all network addressing
       stripped off. See also the CCooppyy, ffoolllloowwuupp, and FFoolllloowwuupp commands and
       oouuttffoollddeerr variable.

   SSeett VVaarriiaabblleess
       _S_y_n_o_p_s_i_s:

                     se[[t]] [[_n_a_m_e[[=[[_s_t_r_i_n_g]]]] ...]] [[_n_a_m_e=_n_u_m_b_e_r ...]] [[no_n_a_m_e ...]]

       Define one or more variables called _n_a_m_e.  The variable can be given a
       null, string, or numeric value. Quoting and <backslash>-escapes can
       occur anywhere in _s_t_r_i_n_g, as described previously, as if the _s_t_r_i_n_g
       portion of the argument were the entire argument. The forms _n_a_m_e and
       _n_a_m_e= shall be equivalent to _n_a_m_e="" for variables that take string
       values. The sseett command without arguments shall write a list of all
       defined variables and their values. The nnoo _n_a_m_e form shall be
       equivalent to uunnsseett _n_a_m_e.

   IInnvvookkee aa SShheellll
       _S_y_n_o_p_s_i_s:

                     sh[[ell]]

       Invoke an interactive command interpreter (see also _S_H_E_L_L).

   DDiissppllaayy MMeessssaaggee SSiizzee
       _S_y_n_o_p_s_i_s:

                     si[[ze]] [[_m_s_g_l_i_s_t]]

       Write the size in bytes of each of the specified messages.

   RReeaadd mmaaiillxx CCoommmmaannddss FFrroomm aa FFiillee
       _S_y_n_o_p_s_i_s:

                     so[[urce]] _f_i_l_e

       Read and execute commands from the file named by the pathname _f_i_l_e and
       return to command mode.

   DDiissppllaayy BBeeggiinnnniinngg ooff MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     to[[p]] [[_m_s_g_l_i_s_t]]

       Write the top few lines of each of the specified messages. If the
       ttoopplliinneess variable is set, it is taken as the number of lines to write.
       The default shall be 5.

   TToouucchh MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     tou[[ch]] [[_m_s_g_l_i_s_t]]

       Touch the specified messages. If any message in _m_s_g_l_i_s_t is not
       specifically deleted nor saved in a file, it shall be placed in the
       mmbbooxx upon normal termination. See eexxiitt and qquuiitt.

   DDeelleettee AAlliiaasseess
       _S_y_n_o_p_s_i_s:

                     una[[lias]] [[_a_l_i_a_s]]...

       Delete the specified alias names. If a specified alias does not exist,
       the results are unspecified.

   UUnnddeelleettee MMeessssaaggeess
       _S_y_n_o_p_s_i_s:

                     u[[ndelete]] [[_m_s_g_l_i_s_t]]

       Change the state of the specified messages from deleted to read. If
       aauuttoopprriinntt is set, the last message of those restored shall be written.
       If _m_s_g_l_i_s_t is not specified, the message shall be selected as follows:

        *  If there are any deleted messages that follow the current message,
           the first of these shall be chosen.

        *  Otherwise, the last deleted message that also precedes the current
           message shall be chosen.

   UUnnsseett VVaarriiaabblleess
       _S_y_n_o_p_s_i_s:

                     uns[[et]] _n_a_m_e...

       Cause the specified variables to be erased.

   EEddiitt MMeessssaaggee wwiitthh FFuullll--SSccrreeeenn EEddiittoorr
       _S_y_n_o_p_s_i_s:

                     v[[isual]] [[_m_s_g_l_i_s_t]]

       Edit the given messages with a screen editor. Each message shall be
       placed in a temporary file, and the utility named by the _V_I_S_U_A_L
       variable shall be invoked to edit each file in sequence. The default
       editor shall be _v_i.

       The vviissuuaall command does not modify the contents of those messages in
       the mailbox.

   WWrriittee MMeessssaaggeess ttoo aa FFiillee
       _S_y_n_o_p_s_i_s:

                     w[[rite]] [[_m_s_g_l_i_s_t]] _f_i_l_e

       Write the given messages to the file specified by the pathname _f_i_l_e,
       minus the message header. Otherwise, it shall be equivalent to the ssaavvee
       command.

   SSccrroollll HHeeaaddeerr DDiissppllaayy
       _S_y_n_o_p_s_i_s:

                     z[[+|-]]

       Scroll the header display forward (if ''++'' is specified or if no option
       is specified) or backward (if ''--'' is specified) one screenful. The
       number of headers written shall be set by the ssccrreeeenn variable.

   IInnvvookkee SShheellll CCoommmmaanndd
       _S_y_n_o_p_s_i_s:

                     !_c_o_m_m_a_n_d

       Invoke the command interpreter specified by _S_H_E_L_L with two arguments:
       --cc and _c_o_m_m_a_n_d.  (See also _s_h --cc.)  If the bbaanngg variable is set, each
       unescaped occurrence of ''!!''  in _c_o_m_m_a_n_d shall be replaced with the
       command executed by the previous !!  command or ~~!!  command escape.

   NNuullll CCoommmmaanndd
       _S_y_n_o_p_s_i_s:

                     # _c_o_m_m_e_n_t

       This null command (comment) shall be ignored by _m_a_i_l_x.

   DDiissppllaayy CCuurrrreenntt MMeessssaaggee NNuummbbeerr
       _S_y_n_o_p_s_i_s:

                     =

       Write the current message number.

   CCoommmmaanndd EEssccaappeess iinn mmaaiillxx
       The following commands can be entered only from input mode, by
       beginning a line with the escape character (by default, <tilde> (''~~'')).
       See the eessccaappee variable description for changing this special
       character. The format for the commands shall be:


           <_e_s_c_a_p_e_-_c_h_a_r_a_c_t_e_r><_c_o_m_m_a_n_d_-_c_h_a_r><_s_e_p_a_r_a_t_o_r>[[<_a_r_g_u_m_e_n_t_s>]]

       where the <_s_e_p_a_r_a_t_o_r> can be zero or more <blank> characters.

       In the following descriptions, the application shall ensure that the
       argument _c_o_m_m_a_n_d (but not _m_a_i_l_x_-_c_o_m_m_a_n_d_) is a shell command string. Any
       string acceptable to the command interpreter specified by the _S_H_E_L_L
       variable when it is invoked as _S_H_E_L_L --cc _c_o_m_m_a_n_d___s_t_r_i_n_g shall be valid.
       The command can be presented as multiple arguments (that is, quoting is
       not required).

       Command escapes that are listed with _m_s_g_l_i_s_t or _m_a_i_l_x_-_c_o_m_m_a_n_d arguments
       are invalid in Send Mode and produce unspecified results.

       ~~!! _c_o_m_m_a_n_d
                 Invoke the command interpreter specified by _S_H_E_L_L with two
                 arguments: --cc and _c_o_m_m_a_n_d; and then return to input mode. If
                 the bbaanngg variable is set, each unescaped occurrence of ''!!''
                 in _c_o_m_m_a_n_d shall be replaced with the command executed by the
                 previous !!  command or ~~!!  command escape.

       ~~..        Simulate end-of-file (terminate message input).

       ~~:: _m_a_i_l_x_-_c_o_m_m_a_n_d, ~~__ _m_a_i_l_x_-_c_o_m_m_a_n_d
                 Perform the command-level request.

       ~~??        Write a summary of command escapes.

       ~~AA        This shall be equivalent to ~~ii SSiiggnn.

       ~~aa        This shall be equivalent to ~~ii ssiiggnn.

       ~~bb _n_a_m_e...
                 Add the _n_a_m_es to the blind carbon copy (BBcccc) list.

       ~~cc _n_a_m_e...
                 Add the _n_a_m_es to the carbon copy (CCcc) list.

       ~~dd        Read in the dead-letter file. See _D_E_A_D for a description of
                 this file.

       ~~ee        Invoke the editor, as specified by the _E_D_I_T_O_R environment
                 variable, on the partial message.

       ~~ff [[_m_s_g_l_i_s_t]]
                 Forward the specified messages. The specified messages shall
                 be inserted into the current message without alteration. This
                 command escape also shall insert message headers into the
                 message with field selection affected by the ddiissccaarrdd, iiggnnoorree,
                 and rreettaaiinn commands.

       ~~FF [[_m_s_g_l_i_s_t]]
                 This shall be the equivalent of the ~~ff command escape, except
                 that all headers shall be included in the message, regardless
                 of previous ddiissccaarrdd, iiggnnoorree, and rreettaaiinn commands.

       ~~hh        If standard input is a terminal, prompt for a SSuubbjjeecctt line
                 and the TToo, CCcc, and BBcccc lists. Other implementation-defined
                 headers may also be presented for editing. If the field is
                 written with an initial value, it can be edited as if it had
                 just been typed.

       ~~ii _s_t_r_i_n_g Insert the value of the named variable, followed by a
                 <newline>, into the text of the message. If the string is
                 unset or null, the message shall not be changed.

       ~~mm [[_m_s_g_l_i_s_t]]
                 Insert the specified messages into the message, prefixing
                 non-empty lines with the string in the iinnddeennttpprreeffiixx variable.
                 This command escape also shall insert message headers into
                 the message, with field selection affected by the ddiissccaarrdd,
                 iiggnnoorree, and rreettaaiinn commands.

       ~~MM [[_m_s_g_l_i_s_t]]
                 This shall be the equivalent of the ~~mm command escape, except
                 that all headers shall be included in the message, regardless
                 of previous ddiissccaarrdd, iiggnnoorree, and rreettaaiinn commands.

       ~~pp        Write the message being entered. If the message is longer
                 than ccrrtt lines (see _I_n_t_e_r_n_a_l _V_a_r_i_a_b_l_e_s _i_n _m_a_i_l_x), the output
                 shall be paginated as described for the _P_A_G_E_R variable.

       ~~qq        Quit (see the qquuiitt command) from input mode by simulating an
                 interrupt. If the body of the message is not empty, the
                 partial message shall be saved in the dead-letter file. See
                 _D_E_A_D for a description of this file.

       ~~rr _f_i_l_e, ~~<< _f_i_l_e, ~~rr !!_c_o_m_m_a_n_d, ~~<< !!_c_o_m_m_a_n_d
                 Read in the file specified by the pathname _f_i_l_e.  If the
                 argument begins with an <exclamation-mark> (''!!''), the rest of
                 the string shall be taken as an arbitrary system command; the
                 command interpreter specified by _S_H_E_L_L shall be invoked with
                 two arguments: --cc and _c_o_m_m_a_n_d.  The standard output of
                 _c_o_m_m_a_n_d shall be inserted into the message.

       ~~ss _s_t_r_i_n_g Set the subject line to _s_t_r_i_n_g.

       ~~tt _n_a_m_e...
                 Add the given _n_a_m_es to the TToo list.

       ~~vv        Invoke the full-screen editor, as specified by the _V_I_S_U_A_L
                 environment variable, on the partial message.

       ~~ww _f_i_l_e   Write the partial message, without the header, onto the file
                 named by the pathname _f_i_l_e.  The file shall be created or the
                 message shall be appended to it if the file exists.

       ~~xx        Exit as with ~~qq, except the message shall not be saved in the
                 dead-letter file.

       ~~|| _c_o_m_m_a_n_d
                 Pipe the body of the message through the given _c_o_m_m_a_n_d by
                 invoking the command interpreter specified by _S_H_E_L_L with two
                 arguments: --cc and _c_o_m_m_a_n_d.  If the _c_o_m_m_a_n_d returns a
                 successful exit status, the standard output of the command
                 shall replace the message. Otherwise, the message shall
                 remain unchanged. If the _c_o_m_m_a_n_d fails, an error message
                 giving the exit status shall be written.

EEXXIITT SSTTAATTUUSS
       When the --ee option is specified, the following exit values are
       returned:

        0    Mail was found.

       >0    Mail was not found or an error occurred.

       Otherwise, the following exit values are returned:

        0    Successful completion; note that this status implies that all
             messages were _s_e_n_t, but it gives no assurances that any of them
             were actually _d_e_l_i_v_e_r_e_d.

       >0    An error occurred.

CCOONNSSEEQQUUEENNCCEESS OOFF EERRRROORRSS
       When in input mode (Receive Mode) or Send Mode:

        *  If an error is encountered processing an input line beginning with
           a <tilde> (''~~'') character, (see _C_o_m_m_a_n_d _E_s_c_a_p_e_s _i_n _m_a_i_l_x), a
           diagnostic message shall be written to standard error, and the
           message being composed may be modified, but this condition shall
           not prevent the message from being sent.

        *  Other errors shall prevent the sending of the message.

       When in command mode:

        *  Default.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       Delivery of messages to remote systems requires the existence of
       communication paths to such systems. These need not exist.

       Input lines are limited to {LINE_MAX} bytes, but mailers between
       systems may impose more severe line-length restrictions. This volume of
       POSIX.1-2017 does not place any restrictions on the length of messages
       handled by _m_a_i_l_x, and for delivery of local messages the only
       limitations should be the normal problems of available disk space for
       the target mail file. When sending messages to external machines,
       applications are advised to limit messages to less than 100000 bytes
       because some mail gateways impose message-length restrictions.

       The format of the system mailbox is intentionally unspecified. Not all
       systems implement system mailboxes as flat files, particularly with the
       advent of multimedia mail messages. Some system mailboxes may be
       multiple files, others records in a database. The internal format of
       the messages themselves is specified with the historical format from
       Version 7, but only after the messages have been saved in some file
       other than the system mailbox. This was done so that many historical
       applications expecting text-file mailboxes are not broken.

       Some new formats for messages can be expected in the future, probably
       including binary data, bit maps, and various multimedia objects. As
       described here, _m_a_i_l_x is not prohibited from handling such messages,
       but it must store them as text files in secondary mailboxes (unless
       some extension, such as a variable or command line option, is used to
       change the stored format).  Its method of doing so is implementation-
       defined and might include translating the data into text file-
       compatible or readable form or omitting certain portions of the message
       from the stored output.

       The ddiissccaarrdd and iiggnnoorree commands are not inverses of the rreettaaiinn command.
       The rreettaaiinn command discards all header-fields except those explicitly
       retained.  The ddiissccaarrdd command keeps all header-fields except those
       explicitly discarded. If headers exist on the retained header list,
       ddiissccaarrdd and iiggnnoorree commands are ignored.

EEXXAAMMPPLLEESS
       None.

RRAATTIIOONNAALLEE
       The standard developers felt strongly that a method for applications to
       send messages to specific users was necessary. The obvious example is a
       batch utility, running non-interactively, that wishes to communicate
       errors or results to a user. However, the actual format, delivery
       mechanism, and method of reading the message are clearly beyond the
       scope of this volume of POSIX.1-2017.

       The intent of this command is to provide a simple, portable interface
       for sending messages non-interactively. It merely defines a ``front-
       end'' to the historical mail system. It is suggested that
       implementations explicitly denote the sender and recipient in the body
       of the delivered message. Further specification of formats for either
       the message envelope or the message itself were deliberately not made,
       as the industry is in the midst of changing from the current standards
       to a more internationalized standard and it is probably incorrect, at
       this time, to require either one.

       Implementations are encouraged to conform to the various delivery
       mechanisms described in the CCITT X.400 standards or to the equivalent
       Internet standards, described in Internet Request for Comment (RFC)
       documents RFC 819, RFC 920, RFC 921, RFC 1123, and RFC 5322 (which
       succeeded RFC 822).

       Many historical systems modified each body line that started with FFrroomm
       by prefixing the ''FF'' with ''>>''.  It is unnecessary, but allowed, to do
       that when the string does not follow a blank line because it cannot be
       confused with the next header.

       The eeddiitt and vviissuuaall commands merely edit the specified messages in a
       temporary file. They do not modify the contents of those messages in
       the mailbox; such a capability could be added as an extension, such as
       by using different command names.

       The restriction on a subject line being {LINE_MAX}-10 bytes is based on
       the historical format that consumes 10 bytes for SSuubbjjeecctt::  and the
       trailing <newline>.  Many historical mailers that a message may
       encounter on other systems are not able to handle lines that long,
       however.

       Like the utilities _l_o_g_g_e_r and _l_p, _m_a_i_l_x admittedly is difficult to
       test. This was not deemed sufficient justification to exclude this
       utility from this volume of POSIX.1-2017. It is also arguable that it
       is, in fact, testable, but that the tests themselves are not portable.

       When _m_a_i_l_x is being used by an application that wishes to receive the
       results as if none of the User Portability Utilities option features
       were supported, the _D_E_A_D environment variable must be set to //ddeevv//nnuullll.
       Otherwise, it may be subject to the file creations described in _m_a_i_l_x
       ASYNCHRONOUS EVENTS. Similarly, if the _M_A_I_L_R_C environment variable is
       not set to //ddeevv//nnuullll, historical versions of _m_a_i_l_x and _M_a_i_l read
       initialization commands from a file before processing begins.  Since
       the initialization that a user specifies could alter the contents of
       messages an application is trying to send, such applications must set
       _M_A_I_L_R_C to //ddeevv//nnuullll.

       The description of _L_C___T_I_M_E uses ``may affect'' because many historical
       implementations do not or cannot manipulate the date and time strings
       in the incoming mail headers. Some headers found in incoming mail do
       not have enough information to determine the timezone in which the mail
       originated, and, therefore, _m_a_i_l_x cannot convert the date and time
       strings into the internal form that then is parsed by routines like
       _s_t_r_f_t_i_m_e() that can take _L_C___T_I_M_E settings into account. Changing all
       these times to a user-specified format is allowed, but not required.

       The paginator selected when _P_A_G_E_R is null or unset is partially
       unspecified to allow the System V historical practice of using _p_g as
       the default. Bypassing the pagination function, such as by declaring
       that _c_a_t is the paginator, would not meet with the intended meaning of
       this description. However, any ``portable user'' would have to set
       _P_A_G_E_R explicitly to get his or her preferred paginator on all systems.
       The paginator choice was made partially unspecified, unlike the _V_I_S_U_A_L
       editor choice (mandated to be _v_i) because most historical pagers follow
       a common theme of user input, whereas editors differ dramatically.

       Options to specify addresses as cccc (carbon copy) or bbcccc (blind carbon
       copy) were considered to be format details and were omitted.

       A zero exit status implies that all messages were _s_e_n_t, but it gives no
       assurances that any of them were actually _d_e_l_i_v_e_r_e_d.  The reliability
       of the delivery mechanism is unspecified and is an appropriate
       marketing distinction between systems.

       In order to conform to the Utility Syntax Guidelines, a solution was
       required to the optional _f_i_l_e option-argument to --ff.  By making _f_i_l_e an
       operand, the guidelines are satisfied and users remain portable.
       However, it does force implementations to support usage such as:


           mailx -fin mymail.box

       The nnoo _n_a_m_e method of unsetting variables is not present in all
       historical systems, but it is in System V and provides a logical set of
       commands corresponding to the format of the display of options from the
       _m_a_i_l_x _s_e_t command without arguments.

       The aasskk and aasskkssuubb variables are the names selected by BSD and System
       V, respectively, for the same feature. They are synonyms in this volume
       of POSIX.1-2017.

       The _m_a_i_l_x _e_c_h_o command was not documented in the BSD version and has
       been omitted here because it is not obviously useful for interactive
       users.

       The default prompt on the System V _m_a_i_l_x is a <question-mark>, on BSD
       _M_a_i_l an <ampersand>.  Since this volume of POSIX.1-2017 chose the _m_a_i_l_x
       name, it kept the System V default, assuming that BSD users would not
       have difficulty with this minor incompatibility (that they can
       override).

       The meanings of rr and RR are reversed between System V _m_a_i_l_x and SunOS
       _M_a_i_l.  Once again, since this volume of POSIX.1-2017 chose the _m_a_i_l_x
       name, it kept the System V default, but allows the SunOS user to
       achieve the desired results using fflliipprr, an internal variable in System
       V _m_a_i_l_x, although it has not been documented in the SVID.

       The iinnddeennttpprreeffiixx variable, the rreettaaiinn and uunnaalliiaass commands, and the ~~FF
       and ~~MM command escapes were adopted from 4.3 BSD _M_a_i_l.

       The vveerrssiioonn command was not included because no sufficiently general
       specification of the version information could be devised that would
       still be useful to a portable user. This command name should be used by
       suppliers who wish to provide version information about the _m_a_i_l_x
       command.

       The ``implementation-specific (unspecified) system start-up file''
       historically has been named //eettcc//mmaaiillxx..rrcc, but this specific name and
       location are not required.

       The intent of the wording for the nneexxtt command is that if any command
       has already displayed the current message it should display a following
       message, but, otherwise, it should display the current message.
       Consider the command sequence:


           next 3
           delete 3
           next

       where the aauuttoopprriinntt option was not set. The normative text specifies
       that the second nneexxtt command should display a message following the
       third message, because even though the current message has not been
       displayed since it was set by the ddeelleettee command, it has been displayed
       since the current message was anything other than message number 3.
       This does not always match historical practice in some implementations,
       where the command file address followed by nneexxtt (or the default
       command) would skip the message for which the user had searched.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _C_h_a_p_t_e_r _2, _S_h_e_l_l _C_o_m_m_a_n_d _L_a_n_g_u_a_g_e, _e_d, _l_s, _m_o_r_e, _v_i

       The Base Definitions volume of POSIX.1-2017, _C_h_a_p_t_e_r _8, _E_n_v_i_r_o_n_m_e_n_t
       _V_a_r_i_a_b_l_e_s, _S_e_c_t_i_o_n _1_2_._2, _U_t_i_l_i_t_y _S_y_n_t_a_x _G_u_i_d_e_l_i_n_e_s

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                             MAILX(1)
