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       avenger.local - deliver mail for a local user


       avenger.local [-f sender] [-D recip] [-a extra] [-d] user


       avenger.local is a local mail delivery agent that enables users to set
       up multiple "extension" email addresses and process mail differently
       for each addresses.  The popular qmail MTA (<>)
       has a mechanism for processing such extension addresses.  avenger.local
       provides a similar facility for users of other MTAs, such as sendmail.

       To use avenger.local, you should configure your MTA so that it delivers
       mail to user+extra@host by executing avenger.local -D user+extra@host
       -d user+extra.  Alternatively, you can execute avenger.local -a extra
       -d user, but then you lose information about the host.  However, the
       latter syntax has the advantage of being command-line compatible with
       procmail; thus, if your MTA has support for procmail as a local
       delivery agent, you should be able to use that by simply substituting
       avenger.local’s path for procmail’s.

       Note that either way you invoke it, avenger.local rejects recipients
       containing the string ".." in the local part.  Such mailbox names are
       not allowed by RFC822, and could potentially lead to security problems
       if parts of mailbox names are used as file names.  Out of paranoia,
       avenger.local additionally rejects mailbox names containing the "/"
       character in the extra portion after the local username.

       avenger.local is designed to be unobtrusive for users who do not want
       to take advantage of its functionality.  When delivering mail for user,
       if user’s home directory does not contain a subdirectory .avenger,
       avenger.local simply executes the default mail delivery agent (usually
       called mail.local).

       For users who do have .avenger directories, mail is delivered according
       to rule files called .avenger/local*.  Mail to user@host is delivered
       according to rules in .avenger/local.  Mail to user+ext1@host is
       delivered according to rules in .avenger/local+ext1 if such a file
       exists, or else .avenger/local+default if such a file exists; if
       neither file exists, the mail is bounced.  Addresses containing
       multiple "+" characters are handled as expected.  Mail to
       user+ext1+ext2@host is governed by, in order of decreasing precedence,
       .avenger/local+ext1+ext2, .avenger/local+ext1+default, or
       .avenger/local+default; it is bounced if none of those files exist.

       Local rule files can be in one of two formats.  If the first two
       characters of the file are "#!", then the file is simply executed as a
       script, with the message on standard input.  The script’s standard
       input will be read-only, but seekable, so, for example, the message can
       be delivered to multiple mailboxes using the deliver utility.

       Otherwise, if the first two characters of a file are not "#!",
       avenger.local uses a syntax similar to (but not identical to) qmail’s,
       where each line is one of the following types, depending on the first

       # comment
           Lines starting with "#" are treated as comments and ignored.  The
           exception is that if the first line begins "#!", the file is
           executed as a script.  Note that if the first two characters of a
           file are "#!" but the file’s execute permission bits are not set,
           then mail sent to that address will be deferred.  (This mechanism
           can be used for intentionally deferring mail while performing

           A line starting "." or "/" and ending with a "/" character is
           treated as a mail directory.  Mail is delivered there using the
           qmail maildir format.

           A line starting "." or "/" and NOT ending with a "/" character
           specifies an ordinary Unix mbox file into which the message should
           be delivered.

           "&" indicates that a copy of the message should be forwarded to
           address.  You may not place a space between & and address, nor can
           address contain angle brackets, comments, or anything other than an
           email address with a fully-qualified domain name.

           (Note that in qmail, the & character is optional for certain email
           addresses, while avenger.local always requires the & character.)

           Forwarding happens after all other lines in the file are processed.
           If any other configuration line fails, for instance because a
           command executed on behalf of a | line exits non-zero, the mail is
           not forwarded to any of the addresses.  (The exception is if a
           command exits with status 99, in which case mail is forwarded to
           addresses in all preceding & lines, but subsequent lines are

       | command
           Specifies that command should be run as a shell command, with the
           mail message as its standard input.  If command exits with a status
           other than 0, processing of the local rule file terminates
           immediately, with avenger.local’s exit status determined by

           If command’s status is 99, avenger.local exits with status 0,
           effectively pretending the command just executed was the last line
           in the .avenger/local* file.  If command’s exit status is between
           64 and 78, inclusive, avenger.local exits with the same status as
           command.  If command exits with status 100 or 112, avenger.local
           exits with status 70.  For all other exit values, or if command
           terminates because of a signal, avenger.local exits with status 75.
           Note that the --qmailexit flag changes this behavior, as described

           See the file /usr/include/sysexits.h for more information on the
           meaning of various exit statuses to sendmail.

           This sets the envelope sender (i.e., bounce address) for copies of
           the message forwarded to users with & lines.  Note that one sender
           address applies to all recipients, regardless of where in the
           .avenger/local* file the bounce address is set.  It is not possible
           to forward from different bounce addresses for different

           The first form of this line simply sets the envelope sender to
           address.  No spaces are allowed between < and the address.  No
           angle brackets or comments are allowed either.

           The second form of this line executes command with the shell,
           giving it the message body as standard input.  If command exits
           with status 0 and outputs exactly one line of text, this line will
           be interpreted as the new envelope sender for forwarded copies the
           message.  If command exits with any of statuses 64-78, 99-100, or
           111-112, processing of the avenger/.local* halts exactly as for the
           | command.  For other exit statuses, or if command outputs no lines
           or more than one line, the command’s result is ignored and
           processing continues with the envelope sender unchanged.

       ! command
           Runs command with the shell, giving it the mail message on standard
           input.  If the command exits 0 and outputs exactly one line of text
           beginning "." or "/", the output is interpreted as either a maildir
           (if the line ends "/") or a mailbox (if it doesn’t) to which the
           message should be delivered.  In other cases, either the ! line is
           ignored, or processing halts, as described for the <! command.

       A completely empty file (not even containing a comment or blank line),
       or a missing .avenger/local (with no extension file), is treated as
       equivalent to a file with the line "./Mailbox".

       -a extra
           Specifies the extra portion of the local part of the email address
           after the user name.  In other words, if avenger.local is invoked
           with arguments -a extra -d user, it is equivalent to invoking it
           with the arguments -d user+extra.  The -a option allows command-
           line compatibility with sendmail’s procmail interface, which
           separates out the user name from the extension portion of the

       -d user
           Specifies the local user to deliver mail to.  Note that for
           compatibility with other local mailers, the -d is optional, you can
           simply specify user as the final command-line argument.

       -f sender
       -r sender
           The -f option specifies the envelope sender of the message.  For
           historical reasons, -r is synonymous with -f.

       -t  This option is silently ignored, for command-line compatibility
           with procmail.

       -B  Ordinarily, when forwarding a bounce message, avenger.local will
           invoke sendmail with the argument -f followed by an empty string
           argument (i.e., specifying an empty from address).  This does not
           work with some older versions of sendmail.  The -B option says that
           bounce messages should be forwarded with arguments -f @ instead,
           which appears to produce the desired (MAILER-DAEMON) result with
           older versions of sendmail.

       -Y  This option is silently ignored, for command-line compatibility
           with procmail.

       --fallback program
           If the user specified on the command line does not exist or have a
           $HOME/.avenger/ directory, or else has UID 0 (root), or has an
           invalid shell or an expired account, then avenger.local will not
           attempt to deliver mail to the user.  Instead, it will attempt to
           run the system’s normal mail delivery agent as a fallback.  This
           program is usually called mail.local, but you can specify an
           alternative with the --falback option.  Note that this should be
           the full path of the program, and should not contain any arguments.
           avenger.local will supply the arguments -f from -d user.

           This option enables fcntl (a.k.a. POSIX) file locking of mail
           spools, in addition to flock and dotfile locking.  The advantage of
           fcntl locking is that it may do the right thing over NFS.  However,
           if either the NFS client or server does not properly support fcntl
           locking, or the file system is not mounted with the appropriate
           options, fcntl locking can fail in one of several ways.  It can
           allow different processes to lock the same file concurrently--even
           on the same machine.  It can simply hang when trying to acquire a
           lock, even if no other process holds a lock on the file.  Also, on
           some OSes it can interact badly with flock locking, because those
           OSes actually implement flock in terms of fcntl.  For these
           reasons, avenger.local performs dotfile and flock locking by
           default, but not fcntl locking.

           When programs from |, !, and <! exit with non-zero exit status, the
           --qmailexit flag causes avenger.local to translate the exit codes
           to ones more suitable for qmail.  Any code that would cause a hard
           error in sendmail causes avenger.local to exit with 100, any soft
           error causes exit code 111, and exit code 99 is passed through.

       --sendmail program
           Specifies the program to run to send mail, when users have lines
           beginning "&" in their .avenger/local* files.  If program contains
           spaces, it is broken into multiple arguments.  The default value
           for program is "sendmail -oi -os -oee".

       --separator char
           Specifies a separator character to place between portions of the
           address extension.  The default value is "+".  Thus, the argument
           -a a+b would cause avenger.local to search for files
           $HOME/.avenger/local+a+b, $HOME/.avenger/local+a+default, and
           $HOME/.avenger/local+default.  Specifying a different char, say
           "-", would change the "+" to "-" in both the email address and file

       --smuser user
           By default, sendmail is run as the user under which avenger.local
           is invoked, which will ordinarily be root.  To drop privileges
           before running sendmail, you can specify this argument and
           avenger.local will run sendmail as user.  Note that avenger doesn’t
           run sendmail as the recipient user, because this often results in
           undesirable "X-Authentication-Warning" fields in the header.  If
           you wish the header to reflect a trail of how a message has been
           forwarded, see the --to option below.

       --tmpfile template
           avenger.local creates a copy of the message in a local file.
           template is a template for the name of the file, which must end
           with a number of "X" characters, which will be replaced by a unique
           identifier.  (This is for use with the mkstemp(3) library call.)
           The default value is "/tmp/msg.XXXXXXXXXX".

       --to address (-D address)
           Specifies the full envelope recipient address to which this message
           is being delivered.  With this option, avenger.local adds a line
           "Delivered-To:  address" to the header of the mail message.  It
           also checks that the header did not previously contain the same
           line--if the message has already been delivered to the same
           address, this indicates a loop, and avenger.local exits with status


       The following environment variables are set when running commands
       specified in lines starting |.

       EXT The local portion of the email address following the first
           separator character (which is the "+" character, unless set
           otherwise by --separator).  This variable is not set if there is no
           extension in the email address.

       EXT1, EXT2, ...
           When EXT itself contains a the separator character, EXT1 contains
           the part of EXT after the first separator, EXT2 the part after the
           second separator, and so on for each separator character in EXT.

           If a recipient has been specified with the -D recip flag, this
           variable will contain the host portion of recip.

           If a recipient has been specified with the -D recip flag, this
           variable will contain the local portion of recip.

       SUFFIX, SUFFIX1, SUFFIX2, ...
           Assuming the separator is "+", when processing a file
           local+base+default, PREFIX is set to base, while SUFFIX is set to
           the portion of the name for which default was substituted.  When
           the file does not end with default, SUFFIX is not set.  When the
           file is just local with no extension, neither PREFIX nor SUFFIX is
           set.  When SUFFIX itself contains a "+" character, SUFFIX1 contains
           to the part of SUFFIX after the first "+" character, SUFFIX2
           contains the part after the second "+", and so on for each "+"
           character in suffix.

           If the --to option was specified, the RECIPIENT environment
           variable is set to the address specified in that option.
           Otherwise, RECIPIENT is not set.

           These are the same as HOST and LOCAL, but with all characters
           folded to lower-case.

           A "Return-Path:" line suitable for prepending to the message

           The envelope sender of the message.

           The value of the --sendmail option, or "sendmail -oi -os -oee" by

           This is the same as $SENDER, unless envelope sender is empty (for a
           bounce message) and the -B option has been specified, in which case
           SENDFROM is "@".  You can forward a message on from the same sender
           with a line like this:

                | $SENDMAIL -f "$SENDFROM" -- ...

           The separator character specified by --separator, or the default
           "+" if none has been explicitly specified.

           An mbox "From " line suitable for prepending to the message before
           appending it to a mailbox or passing it to a filter that expects
           such a line.

           The user to whom the message is being delivered.


       To use avenger.local with sendmail, you might put the following in your
       sendmail m4 configuration file (this is the file ending .mc that
       produces your file):

                       `avenger.local -a $h -d $u')

       To deliver mail to a maildir directory called inbox in your home
       directory, you would place the following line in the file


       If you are subscribed to several mailing lists, you might wish to spool
       them in separate files, so as to read them separately.  (For example,
       the emacs editor has a newsreader, GNUS, that lets you read multiple
       mailboxes more like newsgroups.)  To do this, you should subscribe to
       each mailing list under a different address.  If your address is
       user@host, you might subscribe to the Mail Avenger mailing list as
       user+avenger@host.  To spool mail in file
       $HOME/Mail/incoming/avenger-list.spool, create a file
       $HOME/Mail/.avenger/local+avenger with the following line:


       To create a mailing list user+friends@host for yourself and your
       friends, create a file $HOME/Mail/.avenger/local+friends with your
       inbox and their addresses, for example:



       /usr/local/libexec/avenger.local, $HOME/.avenger/local,
       $HOME/.avenger/local*, /etc/mail/,


       avenger(1), deliver(1), dotlock(1), mail.local(8)

       The Mail Avenger home page: <>.


       avenger.local doesn’t necessarily report problems in a the most useful
       place when it encounters errors in a .avenger/local* file.  It does
       send some diagnostics to standard error, but these will typically end
       up in the mail log or in bounce messages returned to the sender.

       avenger.local should always provide the exact envelope recipient in the
       RECIPIENT environment variable.  Unfortunately, this information is not
       available unless it has been supplied with the -D flag.  Often the
       envelope recipient is just "${USER}${SEPARATOR}${EXT}",
       but it might not be if there are aliases or virtual domains.  On
       servers with virtual hosts, the actual hostname used will be
       unavailable in the general case (though you may be able to deduce it
       from $USER and $EXT if you know your particular setup).  Note that it
       is possible to configure sendmail to supply the full recipient address.
       Mail avenger comes with example sendmail configuration directives that
       can be included in your m4 configuration file; see

       To protect against concurrent accesses to mbox format files,
       avenger.local uses both flock and dotfiles to lock mailboxes.  However,
       it does not use fcntl/lockf-style locking by default.  Thus, if your
       mail reader exclusively uses fcntl for locking, there will be race
       conditions unless you specify the --fcntl option.


       David Mazieres