mailfilter.sh (Source)

# which maildir is to use?
# set default Maildir
MAILDIR="$HOME/Maildir"
# check if we're called from a .qmail-EXT instead of .qmail
import EXT
if ( $EXT )
{
  # does a vmailmgr user named $EXT exist?
  # if yes, deliver mail to his Maildir instead
  CHECKMAILDIR = `dumpvuser $EXT | grep '^Directory' | awk '{ print $2 }'`
  if ( $CHECKMAILDIR )
  {
    MAILDIR="$HOME/$CHECKMAILDIR"
  }
}
# move spam to .Junk folder
DESTDIR="$MAILDIR"
# Here go the filter rules...
if ( /^X-Rspamd-Bar:\s\+\+\+[+]/:h )
{
  DESTDIR="$MAILDIR/.Junk"
}
elsif ( /^List-ID:.*/:h )
{
DESTDIR="$MAILDIR/.newsletters"
}
elsif ( /^Delivered-To:.*-*@.*$/:h )
{
  DESTDIR="$MAILDIR/.services"
}
# Hierarchically create DESTDIR if it does not already exist.
HIER="$DESTDIR"
CONTINUE=1
while ( $CONTINUE && $HIER =~ /^(.*\/(\.[^.]+)*)(\.[^.]+)$/ )
{
  if ( $MATCH3 ne ".INBOX" )
  {
    `test -d "$MATCH"`
    if ( $RETURNCODE == 1 )
    {
      `maildirmake "$MATCH"`
    }
    else
    {
      CONTINUE=0
    }
  }
  HIER=$MATCH1
}
# Deliver mail. If SILENT_DESTDIR is set, mark all mail in
# DESTDIR as read.
if ( $SILENT_DESTDIR )
{
  # mark as read
  cc "$DESTDIR"
  `find "$DESTDIR/new/" -mindepth 1 -maxdepth 1 -type f -printf '%f\0' | xargs -0 -I {} mv "$DESTDIR/new/{}" "$DESTDIR/cur/{}:2,S"`
  exit
}
else
{
  to "$DESTDIR"
}