#!/usr/bin/perl -w

# <@LICENSE>
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to you under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at:
# 
#     http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# </@LICENSE>

use strict;
use warnings;
use re 'taint';

use File::Spec;

my $PREFIX          = '@@PREFIX@@';             # substituted at 'make' time
my $DEF_RULES_DIR   = '@@DEF_RULES_DIR@@';      # substituted at 'make' time
my $LOCAL_RULES_DIR = '@@LOCAL_RULES_DIR@@';    # substituted at 'make' time
my $LOCAL_STATE_DIR = '@@LOCAL_STATE_DIR@@';    # substituted at 'make' time

use lib '@@INSTALLSITELIB@@';                   # substituted at 'make' time

BEGIN {
  # Locate locally installed SA libraries *without* using FindBin, which
  # generates warnings and causes more trouble than its worth.  We don't
  # need to be too smart about this BTW.
  my @bin = File::Spec->splitpath($0);
  my $bin = (
    $bin[0]
    ? File::Spec->catpath( @bin[ 0 .. 1 ] )
    : $bin[1]
    )                                           # /home/jm/foo -> /home/jm
    || File::Spec->curdir;                      # foo          -> .

  # check to make sure it wasn't just installed in the normal way.
  # note that ./lib/Mail/SpamAssassin.pm takes precedence, for
  # building SpamAssassin on a machine where an old version is installed.
  if (-e $bin.'/lib/Mail/SpamAssassin.pm'
        || !-e '@@INSTALLSITELIB@@/Mail/SpamAssassin.pm' )
  {
    my $searchrelative;
    $searchrelative = 1;    # disabled during "make install": REMOVEFORINST

    # Firstly, are we running "make test" in the "t" dir?  the test files
    # *need* to use 'blib', so that 'use bytes' is removed for pre-5.6 perls
    # beforehand by the preproc.  However, ./spamassassin does not, as the
    # preproc will have stripped out the "use rule files from cwd" code from
    # Mail::SpamAssassin.  So we want to use blib just for the t scripts.
    # This is disabled during the "make install" process.
    if ($searchrelative && $bin eq '../' && -e '../blib/lib/Mail/SpamAssassin.pm')
    {
      unshift ( @INC, '../blib/lib' );
    } else {
      # These are common paths where the SA libs might be found.
      foreach ( qw(lib ../lib/site_perl
                ../lib/spamassassin ../share/spamassassin/lib))
      {
        my $dir = File::Spec->catdir( $bin, split ( '/', $_ ) );
        if ( -f File::Spec->catfile( $dir, "Mail", "SpamAssassin.pm" ) )
        { unshift ( @INC, $dir ); last; }
      }
    }
  }
}

use Getopt::Long;
use Pod::Usage;
use Mail::SpamAssassin;
use Mail::SpamAssassin::ArchiveIterator;
use Mail::SpamAssassin::Util::Progress;
use Mail::SpamAssassin::Logger qw(log_message);

BEGIN {
  # redirect __WARN__, but NOT until after the
  # Mail::SpamAssassin::Logger class has been parsed.
  # do not trap warnings here based on eval scope; evals are very
  # common throughout.  die()s can be trapped in future though.
  $SIG{__WARN__} = sub {
    log_message("warn", $_[0]);
  };
};

my %resphash = (
  EX_OK          => 0,     # no problems
  EX_USAGE       => 64,    # command line usage error
  EX_DATAERR     => 65,    # data format error
  EX_NOINPUT     => 66,    # cannot open input
  EX_NOUSER      => 67,    # addressee unknown
  EX_NOHOST      => 68,    # host name unknown
  EX_UNAVAILABLE => 69,    # service unavailable
  EX_SOFTWARE    => 70,    # internal software error
  EX_OSERR       => 71,    # system error (e.g., can't fork)
  EX_OSFILE      => 72,    # critical OS file missing
  EX_CANTCREAT   => 73,    # can't create (user) output file
  EX_IOERR       => 74,    # input/output error
  EX_TEMPFAIL    => 75,    # temp failure; user is invited to retry
  EX_PROTOCOL    => 76,    # remote error in protocol
  EX_NOPERM      => 77,    # permission denied
  EX_CONFIG      => 78,    # configuration error
);


sub print_version {
  print "SpamAssassin version " . Mail::SpamAssassin::Version() . "\n"
      . "  running on Perl version " . join(".", map { $_||=0; $_*1 } ($] =~ /(\d)\.(\d{3})(\d{3})?/ )) . "\n"
    or die "error writing: $!";
}

sub print_usage_and_exit {
  my ( $message, $respnam ) = @_;
  $respnam ||= 'EX_USAGE';

  if ($respnam eq 'EX_OK' ) {
    print_version();
    print("\n")  or die "error writing: $!";
  }
  pod2usage(
    -verbose => 0,
    -message => $message,
    -exitval => $resphash{$respnam},
    -input => "spamassassin-run.pod",
    -pathlist => \@INC,
  );
}


sub usage {
  my ( $verbose, $message ) = @_;
  my $ver = Mail::SpamAssassin::Version();

  print "SpamAssassin version $ver\n"  or die "error writing: $!";
  pod2usage( -verbose => $verbose, -message => $message, -exitval => 64, -input => "spamassassin-run.pod", -pathlist => \@INC );

}

# Check to make sure the script version and the module version matches.
# If not, die here!  Also, deal with unchanged VERSION macro.
if ($Mail::SpamAssassin::VERSION ne '@@VERSION@@' && '@@VERSION@@' ne "\@\@VERSION\@\@") {
  die 'spamassassin: spamassassin script is v@@VERSION@@, but using modules v'.$Mail::SpamAssassin::VERSION."\n";
}

# by default:
# - create user preference files
# - have ArchiveIterator detect the input message format (file vs dir)
#
my %opt = ( 'create-prefs' => 1, 'format' => 'detect', cf => [] );

my $doing_whitelist_operation = 0;
my $count                     = 0;
my @targets                   = ();
my $exitvalue;

my $init_results              = 0;
my $progress;
my $total_messages            = 0;

# gnu_getopt is not available in Getopt::Long 2.24, see bug 732
# gnu_compat neither.
Getopt::Long::Configure(
  qw(bundling no_getopt_compat no_auto_abbrev no_ignore_case));
GetOptions(
  'add-addr-to-blacklist=s'                 => \$opt{'add-addr-to-blacklist'},
  'add-addr-to-whitelist=s'                 => \$opt{'add-addr-to-whitelist'},
  'add-to-blacklist'                        => \$opt{'add-to-blacklist'},
  'add-to-whitelist|W'                      => \$opt{'add-to-whitelist'},
  'configpath|config-file|config-dir|c|C=s' => \$opt{'configpath'},
  'create-prefs!'                           => \$opt{'create-prefs'},
  'cf=s'                                    => \@{$opt{'cf'}},
  'debug|D:s'                               => \$opt{'debug'},
  'error-code|exit-code|e:i'                => \$opt{'error-code'},
  'help|h|?'                                => \$opt{'help'},
  'ipv4only|ipv4-only|ipv4'                 => \$opt{'force_ipv4'},
  'lint'                                    => \$opt{'lint'},
  'local-only|local|L'                      => \$opt{'local'},
  'mbox'                                    => sub { $opt{'format'} = 'mbox'; },
  'mbx'                                     => sub { $opt{'format'} = 'mbx'; },
  'prefspath|prefs-file|p=s'                => \$opt{'prefspath'},
  'remove-addr-from-whitelist=s'            => \$opt{'remove-addr-from-whitelist'},
  'remove-from-whitelist|R'                 => \$opt{'remove-from-whitelist'},
  'remove-markup|despamassassinify|d'       => \$opt{'remove-markup'},
  'report|r'                                => \$opt{'report'},
  'revoke|k'                                => \$opt{'revoke'},
  'siteconfigpath=s'                        => \$opt{'siteconfigpath'},
  'test-mode|test|t'                        => \$opt{'test-mode'},
  'progress'                                => \$opt{'progress'},
  'version|V'                               => \$opt{'version'},
  'x'                                       => sub { $opt{'create-prefs'} = 0 },

  #
  # NOTE: These are old options.  We should ignore (but warn about)
  # the ones that are now defaults.  Everything else gets a die (see note2)
  # so the user doesn't get us doing something they didn't expect.
  #
  # NOTE2: 'die' doesn't actually stop the process, GetOptions() catches
  # it, then passes the error on, so we'll end up doing a Usage statement.
  # You can avoid that by doing an explicit exit in the sub.
  #

  # last in 2.3
  'pipe|P'                => sub { warn "The -P option is deprecated as 'pipe mode' is now the default behavior, ignoring.\n" },
  'F:i'                   => sub { warn "The -F option has been removed from spamassassin, please remove from your commandline and re-run.\n"; exit 2; },
  'add-from!'             => sub { warn "The --add-from option has been removed from spamassassin, please remove from your commandline and re-run.\n"; exit 2; },

  # last in 2.4
  'stop-at-threshold|S'   => sub { warn "The -S option has been deprecated and is no longer supported, ignoring.\n" },

  # last in 2.6
  'log-to-mbox|l:s'       => sub { warn "The -l option has been deprecated and is no longer supported, ignoring.\n" },
  'warning-from|w:s'      => sub { warn "The -w option has been removed from spamassassin, please remove from your commandline and re-run.\n"; exit 2; }, 
  'whitelist-factory|M:s' => sub { warn "The -M option has been removed from spamassassin, please remove from your commandline and re-run.\n"; exit 2; },

) or print_usage_and_exit();

if ( defined $opt{'help'} ) {
  print_usage_and_exit("For more information read the spamassassin man page.\n", 'EX_OK');
}
if ( defined $opt{'version'} ) {
  print_version();
  exit($resphash{'EX_OK'});
}

# set debug areas, if any specified (only useful for command-line tools)
if (defined $opt{'debug'}) {
  $opt{'debug'} ||= 'all';
}

if (Mail::SpamAssassin::Util::am_running_on_windows()) {
  binmode(STDIN)  or die "cannot set binmode on STDIN: $!";  # bug 4363
  binmode(STDOUT) or die "cannot set binmode on STDOUT: $!";
}

# bug 5048: --lint should not cause network accesses
if ($opt{'lint'}) { $opt{'local'} = 1; }

# create the tester factory
my $spamtest = new Mail::SpamAssassin(
  {
    rules_filename      => $opt{'configpath'},
    site_rules_filename => $opt{'siteconfigpath'},
    userprefs_filename  => $opt{'prefspath'},
    force_ipv4          => $opt{'force_ipv4'},
    local_tests_only    => $opt{'local'},
    debug               => $opt{'debug'},
    dont_copy_prefs     => ( $opt{'create-prefs'} ? 0 : 1 ),
    post_config_text    => join("\n", @{$opt{'cf'}})."\n",
    require_rules       => 1,
    PREFIX              => $PREFIX,
    DEF_RULES_DIR       => $DEF_RULES_DIR,
    LOCAL_RULES_DIR     => $LOCAL_RULES_DIR,
    LOCAL_STATE_DIR     => $LOCAL_STATE_DIR,
  }
);

if ($opt{'lint'}) {
  $spamtest->debug_diagnostics();
  my $res = $spamtest->lint_rules();
  warn "lint: $res issues detected, please rerun with debug enabled for more information\n" if ($res);
  # make sure we notice any write errors while flushing output buffer
  close STDOUT  or die "error closing STDOUT: $!";
  close STDIN   or die "error closing STDIN: $!";
  exit $res ? 1 : 0;
}

if ($opt{'remove-addr-from-whitelist'} ||
    $opt{'add-addr-to-whitelist'} ||
    $opt{'add-addr-to-blacklist'})
{
  $spamtest->init(1);

  if ( $opt{'add-addr-to-whitelist'} ) {
    $spamtest->add_address_to_whitelist($opt{'add-addr-to-whitelist'}, 1);
  }
  elsif ( $opt{'remove-addr-from-whitelist'} ) {
    $spamtest->remove_address_from_whitelist($opt{'remove-addr-from-whitelist'}, 1);
  }
  elsif ( $opt{'add-addr-to-blacklist'} ) {
    $spamtest->add_address_to_blacklist($opt{'add-addr-to-blacklist'}, 1);
  }
  else {
    die "spamassassin: oops! unhandled whitelist operation";
  }

  $spamtest->finish();
  # make sure we notice any write errors while flushing output buffer
  close STDOUT  or die "error closing STDOUT: $!";
  close STDIN   or die "error closing STDIN: $!";
  exit(0);
}

# if we're going to do white/black-listing, let's prep now...
if ( $opt{'remove-from-whitelist'}
  or $opt{'add-to-whitelist'}
  or $opt{'add-to-blacklist'} )
{
  $doing_whitelist_operation = 1;
  $spamtest->init(1);
}

# if we're doing things in test mode, force disable long-term memory
# functions like autowhitelist and bayes autolearn.
# XXX - feels like we need a plugin hook here so plugins can be made
# aware and take appropriate action.
if ($opt{'test-mode'}) {
  $spamtest->{'conf'}->{'use_auto_whitelist'} = 0;
  $spamtest->{'conf'}->{'bayes_auto_learn'} = 0;
}

###########################################################################
# Deal with the target listing, and STDIN -> tempfile

my $tempfile; # will be defined if stdin -> tempfile
push(@targets, @ARGV);
@targets = ('-') unless @targets;

for(my $elem = 0; $elem <= $#targets; $elem++) {
  # ArchiveIterator doesn't really like STDIN, so if "-" is specified
  # as a target, make it a temp file instead.
  if ( $targets[$elem] =~ /(?:^|:)-$/ ) {
    if (defined $tempfile) {
      # uh-oh, stdin specified multiple times?
      warn "skipping extra stdin target (".$targets[$elem].")\n";
      splice @targets, $elem, 1;
      $elem--; # go back to this element again
      next;
    }
    else {
      my $handle;
      ( $tempfile, $handle ) = Mail::SpamAssassin::Util::secure_tmpfile();
      binmode $handle  or die "cannot set binmode on file $tempfile: $!";

      # avoid slurping the whole file into memory, copy chunk by chunk
      my($inbuf,$nread);
      while ( $nread=sysread(STDIN,$inbuf,16384) )
        { print {$handle} $inbuf  or die "error writing to $tempfile: $!" }
      defined $nread  or die "error reading from STDIN: $!";
      close $handle   or die "cannot close $tempfile: $!";

      # re-aim the targets at the tempfile instead of STDIN
      $targets[$elem] =~ s/-$/$tempfile/;
    }
  }

  # make sure the target list is in the normal AI format
  if ($targets[$elem] !~ /^[^:]*:[a-z]+:/) {
    my $format = $opt{'format'} || 'detect';
    $targets[$elem] = join ( ":", '', $format, $targets[$elem] );
  }
}

###########################################################################

setup_sig_handlers();

# Everything below here needs ArchiveIterator ...
my $iter = new Mail::SpamAssassin::ArchiveIterator(
  {
    'opt_all' => 1,
    'opt_want_date' => 0
  }
);

$iter->set_functions( \&wanted, \&result );

# Go run the messages!
# bug 4930: use a temp variable since "||=" decides whether or not to set the
# value before the RHS is actually run, so if the RHS separately sets the LHS
# variable, things don't work right.  Stupid global variables. ;)
my $eval_stat;
eval {
  my $runreturn = !$iter->run(@targets);  $exitvalue ||= $runreturn;  1;
} or do {
  $eval_stat = $@ ne '' ? $@ : "errno=$!";  chomp $eval_stat;
};

$progress->final() if ($opt{progress} && $progress);

# If we needed to make a tempfile, go delete it now.
if (defined $tempfile) {
  unlink $tempfile  or die "cannot unlink temporary file $tempfile: $!";
  undef $tempfile;
}

# Let folks know how many messages were handled, as long as the handling
# didn't produce output (ala: check, test, or remove_markup ...)
if ( $opt{'report'} || $opt{'revoke'} || $doing_whitelist_operation ) {
  print "$count message(s) examined.\n"  or die "error writing: $!";
}

# if the eval died from something, report it here and return an error.
if (defined $eval_stat) { die $eval_stat; }

$spamtest->finish()  if $spamtest;

# make sure we notice any write errors while flushing output buffer
close STDOUT  or die "error closing STDOUT: $!";
close STDIN   or die "error closing STDIN: $!";
# Ok, exit!
exit( $exitvalue || 0 );

###########################################################################

sub init_results {
  $init_results = 1;

  return unless $opt{'progress'};

  $total_messages = $Mail::SpamAssassin::ArchiveIterator::MESSAGES;

  $progress = Mail::SpamAssassin::Util::Progress->new({total => $total_messages,});
}

###########################################################################

sub result {
  my ($class, $result, $time) = @_;

  # don't open results files until we get here to avoid overwriting files
  &init_results if !$init_results;

  $progress->update($count) if ($opt{progress} && $progress);
}

###########################################################################

my $mail;       # global, so signal handler can clean it up; bug 5626

# make sure it only returns false values so that result_sub() isn't called...
sub wanted {
  my $dataref = $_[3];
  $mail       = $spamtest->parse($dataref);
  $count++;

  # This is a short cut -- doing white/black-list?  Do it and return quickly.
  if ($doing_whitelist_operation) {
    if ( $opt{'add-to-whitelist'} ) {
      $spamtest->add_all_addresses_to_whitelist($mail, 1);
    }
    elsif ( $opt{'remove-from-whitelist'} ) {
      $spamtest->remove_all_addresses_from_whitelist($mail, 1);
    }
    elsif ( $opt{'add-to-blacklist'} ) {
      $spamtest->add_all_addresses_to_blacklist($mail, 1);
    }
    else {
      warn "spamassassin: oops! unhandled whitelist operation";
    }

    $mail->finish();
    $mail = undef;
    return 1;
  }

  # handle removing reports
  if ( $opt{'remove-markup'} ) {

    # If we're not going to retest, just remove the markup and print it out
    if ( !$opt{'test-mode'} ) {
      print $spamtest->remove_spamassassin_markup ($mail);
      $mail->finish();
      $mail = undef;
      return 1;
    }
    else {

      # remove the markup and retest it...  a little more tricky ...
      # go ahead and remove the markup, then fake that the clean version
      # was what was sent in
      #
      my $new_mail =
        $spamtest->parse( $spamtest->remove_spamassassin_markup($mail) );

      $mail->finish();
      $mail = $new_mail;
    }
  }

  # handle reporting and revoking
  if ( $opt{'report'} || $opt{'revoke'} ) {

    # Make sure the message is clean first ...
    my $new_mail =
      $spamtest->parse( $spamtest->remove_spamassassin_markup($mail) );
    $mail->finish();
    $mail = $new_mail;

    my $failed;
    if ( $opt{'report'} && !$spamtest->report_as_spam($mail) ) {
      $failed = 'report';
    }

    if ( $opt{'revoke'} && !$spamtest->revoke_as_spam($mail) ) {
      $failed = 'revoke';
    }

    if ($failed) {
      warn "spamassassin: warning, unable to $failed message\n";
      warn "spamassassin: for more information, re-run with -D option to see debug output\n";
    }

    $mail->finish();
    $mail = undef;
    return 1;
  }

  # OK, do checks and put out the message.
  my $status = $spamtest->check($mail);
  print $status->rewrite_mail()  or die "error writing: $!";

  if ( $opt{'test-mode'} ) {
    use bytes;
    print $status->get_report()  or die "error writing: $!";
  }

  # if this message was spam, set the exit value appropriately.
  if ( defined $opt{'error-code'} && $status->is_spam() && !defined $exitvalue )
  {
    $exitvalue = $opt{'error-code'} || 5;
  }

  # clean up after ourselves
  $mail->finish();
  $mail = undef;

  $status->finish();

  return 1;
}

###########################################################################

sub setup_sig_handlers {
  $SIG{HUP}  = \&kill_handler;
  $SIG{INT}  = \&kill_handler;
  $SIG{TERM} = \&kill_handler;
# $SIG{PIPE} = \&kill_handler;
  $SIG{PIPE} = 'IGNORE';
}

sub kill_handler {
  my ($sig) = @_;
  warn "spamassassin: killed by SIG$sig\n";
  if ($mail) {
    $mail->finish();      # bug 5626: remove temp files etc.
    $mail = undef;
  }
  if (defined $tempfile) {      # bug 5557: additional paranoia about tmpfiles
    unlink $tempfile  or warn "cannot unlink temporary file $tempfile: $!";
    undef $tempfile;
  }
  close STDOUT; close STDIN;  # ignoring status
  exit 15;
}

__END__

# ---------------------------------------------------------------------------

=head1 NAME

spamassassin - extensible email filter used to identify spam

=head1 DESCRIPTION

SpamAssassin is an intelligent email filter which uses a diverse range of
tests to identify unsolicited bulk email, more commonly known as "spam".
These tests are applied to email headers and content to classify email
using advanced statistical methods.  In addition, SpamAssassin has a
modular architecture that allows other technologies to be quickly wielded
against spam and is designed for easy integration into virtually any email
system.

=head1 SYNOPSIS

For ease of access, the SpamAssassin manual has been split up into
several sections.  If you're intending to read these straight through
for the first time, the suggested order will tend to reduce the number
of forward references.

Extensive additional documentation for SpamAssassin is available,
primarily on the SpamAssassin web site and wiki.

You should be able to view SpamAssassin's documentation with your man(1)
program or perldoc(1).

=head2 OVERVIEW

    spamassassin              SpamAssassin overview (this section)

=head2 CONFIGURATION

    Mail::SpamAssassin::Conf  SpamAssassin configuration files

=head2 USAGE

    spamassassin-run          "spamassassin" front-end filtering script
    sa-learn                  train SpamAssassin's Bayesian classifier
    spamc                     client for spamd (faster than spamassassin)
    spamd                     spamassassin server (needed by spamc)

=head2 DEFAULT PLUGINS

@@PLUGIN_POD@@

=head1 WEB SITES

    SpamAssassin web site:     http://spamassassin.apache.org/
    Wiki-based documentation:  http://wiki.apache.org/spamassassin/

=head1 USER MAILING LIST

A users mailing list exists where other experienced users are often able
to help and provide tips and advice.  Subscription instructions are
located on the SpamAssassin web site.

=head1 CONFIGURATION FILES

The SpamAssassin rule base, text templates, and rule description text
are loaded from configuration files.

Default configuration data is loaded from the first existing directory
in:

=over 4

=item @@LOCAL_STATE_DIR@@/@@VERSION@@

=item @@DEF_RULES_DIR@@

=item @@PREFIX@@/share/spamassassin

=item /usr/local/share/spamassassin

=item /usr/share/spamassassin

=back

Site-specific configuration data is used to override any values which had
already been set.  This is loaded from the first existing directory in:

=over 4

=item @@LOCAL_RULES_DIR@@

=item @@PREFIX@@/etc/mail/spamassassin

=item @@PREFIX@@/etc/spamassassin

=item /usr/local/etc/spamassassin

=item /usr/pkg/etc/spamassassin

=item /usr/etc/spamassassin

=item /etc/mail/spamassassin

=item /etc/spamassassin

=back

From those three directories, SpamAssassin will first read files ending in
".pre" in lexical order and then it will read files ending in ".cf" in
lexical order (most files begin with two numbers to make the sorting
order obvious).

In other words, it will read F<init.pre> first, then F<10_default_prefs.cf> before
F<50_scores.cf> and F<20_body_tests.cf> before F<20_head_tests.cf>.
Options in later files will override earlier files.

Individual user preferences are loaded from the location specified on
the C<spamassassin>, C<sa-learn>, or C<spamd> command line (see respective
manual page for details).  If the location is not specified,
F<~/.spamassassin/user_prefs> is used if it exists.  SpamAssassin will
create that file if it does not already exist, using
F<user_prefs.template> as a template.  That file will be looked for in:

=over 4

=item @@LOCAL_RULES_DIR@@

=item @@PREFIX@@/etc/mail/spamassassin

=item @@PREFIX@@/share/spamassassin

=item /etc/spamassassin

=item /etc/mail/spamassassin

=item /usr/local/share/spamassassin

=item /usr/share/spamassassin

=back

=head1 TAGGING

The following two sections detail the default tagging and markup that
takes place for messages when running C<spamassassin> or C<spamc> with
C<spamd> in the default configuration.

Note: before header modification and addition, all headers beginning
with C<X-Spam-> are removed to prevent spammer mischief and also to
avoid potential problems caused by prior invocations of SpamAssassin.

=head2 TAGGING FOR SPAM MAILS

By default, all messages with a calculated score of 5.0 or higher are
tagged as spam.

If an incoming message is tagged as spam, instead of modifying the
original message, SpamAssassin will create a new report message and
attach the original message as a message/rfc822 MIME part (ensuring the
original message is completely preserved and easier to recover).

The new report message inherits the following headers (if they are
present) from the original spam message:

=over 4

=item From: header

=item To: header

=item Cc: header

=item Subject: header

=item Date: header

=item Message-ID: header

=back

The above headers can be modified if the relevant C<rewrite_header>
option is given (see C<Mail::SpamAssassin::Conf> for more information).

By default these message headers are added to spam:

=over 4

=item X-Spam-Flag: header

Set to C<YES>.

=back

The headers that added are fully configurable via the C<add_header>
option (see C<Mail::SpamAssassin::Conf> for more information).

=over 4

=item spam mail body text

The SpamAssassin report is added to top of the mail message body,
if the message is marked as spam.

=back

=head2 DEFAULT TAGGING FOR ALL MAILS

These headers are added to all messages, both spam and ham (non-spam).

=over 4

=item X-Spam-Checker-Version: header

The version and subversion of SpamAssassin and the host where
SpamAssassin was run.

=item X-Spam-Level: header

A series of "*" charactes where each one represents a full score point.

=item X-Spam-Status: header

A string, C<(Yes|No), score=nn required=nn tests=xxx,xxx
autolearn=(ham|spam|no|unavailable|failed)> is set in this header to
reflect the filter status.  For the first word, "Yes" means spam and
"No" means ham (non-spam).

=back

The headers that added are fully configurable via the C<add_header>
option (see C<Mail::SpamAssassin::Conf> for more information).

=head1 INSTALLATION

The B<spamassassin> command is part of the B<Mail::SpamAssassin> Perl module.
Install this as a normal Perl module, using C<perl -MCPAN -e shell>, or by
hand.

Note that it is not possible to use the C<PERL5LIB> environment variable
to affect where SpamAssassin finds its perl modules, due to limitations
imposed by perl's "taint" security checks.

For further details on how to install, please read the C<INSTALL> file
from the SpamAssassin distribution.

=head1 DEVELOPER DOCUMENTATION

    Mail::SpamAssassin
	Spam detector and markup engine

    Mail::SpamAssassin::ArchiveIterator
	find and process messages one at a time

    Mail::SpamAssassin::AutoWhitelist
	auto-whitelist handler for SpamAssassin

    Mail::SpamAssassin::Bayes
	determine spammishness using a Bayesian classifier

    Mail::SpamAssassin::BayesStore
	Bayesian Storage Module

    Mail::SpamAssassin::BayesStore::SQL
	SQL Bayesian Storage Module Implementation

    Mail::SpamAssassin::Conf::LDAP
	load SpamAssassin scores from LDAP database

    Mail::SpamAssassin::Conf::Parser
	parse SpamAssassin configuration

    Mail::SpamAssassin::Conf::SQL
	load SpamAssassin scores from SQL database

    Mail::SpamAssassin::Message
	decode, render, and hold an RFC-2822 message

    Mail::SpamAssassin::Message::Metadata
	extract metadata from a message

    Mail::SpamAssassin::Message::Node
	decode, render, and make available MIME message parts

    Mail::SpamAssassin::PerMsgLearner
	per-message status (spam or not-spam)

    Mail::SpamAssassin::PerMsgStatus
	per-message status (spam or not-spam)

    Mail::SpamAssassin::PersistentAddrList
	persistent address list base class

    Mail::SpamAssassin::Plugin
	SpamAssassin plugin base class

    Mail::SpamAssassin::Plugin::Hashcash
	perform hashcash verification tests

    Mail::SpamAssassin::Plugin::RelayCountry
	add message metadata indicating the country code of each relay

    Mail::SpamAssassin::Plugin::SPF
	perform SPF verification tests

    Mail::SpamAssassin::Plugin::URIDNSBL
	look up URLs against DNS blocklists

    Mail::SpamAssassin::SQLBasedAddrList
	SpamAssassin SQL Based Auto Whitelist

=head1 BUGS

See <http://issues.apache.org/SpamAssassin/>

=head1 AUTHORS

The SpamAssassin(tm) Project <http://spamassassin.apache.org/>

=head1 COPYRIGHT

SpamAssassin is distributed under the Apache License, Version 2.0, as
described in the file C<LICENSE> included with the distribution.