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avenger.local(8)	      Mail Avenger 0.8.5	      avenger.local(8)

NAME
       avenger.local - deliver mail for	a local	user

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

DESCRIPTION
       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 (<http://www.qmail.org/>)
       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
       character:

       # 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
	   maintenance.)

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

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

       &address
	   "&" 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
	   ignored.)

       | 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
	   command's.

	   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
	   below.

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

       <address
       <!command
	   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
	   recipients.

	   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".

   OPTIONS
       -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
	   address.

       -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.

       --fcntl
	   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.

       --qmailexit
	   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
	   names.

       --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
	   70.

ENVIRONMENT
       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.

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

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

       PREFIX
       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.

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

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

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

       SENDER
	   The envelope	sender of the message.

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

       SENDFROM
	   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" -- recpient1@host1.com ...

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

       UFLINE
	   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.

       USER
	   The user to whom the	message	is being delivered.

EXAMPLES
       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 sendmail.cf file):

	       FEATURE(`local_procmail',
		       `/usr/local/libexec/avenger.local',
		       `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
       $HOME/.avenger/local:

	       ./inbox/

       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:

	       ./Mail/incoming/avenger-list.spool

       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:

	     ./inbox/
	     &friend1@host1.com
	     &friend2@host2.com

FILES
       /usr/local/libexec/avenger.local, $HOME/.avenger/local,
       $HOME/.avenger/local*, /etc/mail/sendmail.cf,
       /usr/local/share/avenger/avsendmail.m4

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

       The Mail	Avenger	home page: <http://www.mailavenger.org/>.

BUGS
       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}@your.host.name",
       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 sendmail.mc m4 configuration file; see
       /usr/local/share/avenger/avsendmail.m4.

       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.

AUTHOR
       David Mazieres

Mail Avenger 0.8.5		  2018-10-09		      avenger.local(8)

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | EXAMPLES | FILES | SEE ALSO | BUGS | AUTHOR

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