Vedere man maildropex.

# regex flags, used after the regex: /something/:b
# :h - header
# :b - body
# :D - distinguish between upper and lower case (default is to ignore case)

MAILDIRMAKE="/usr/bin/maildirmake"

# configure for mbox, maildir, or mh
TYPE="maildir"

logfile "$HOME/mailfilter.log"

DEFAULT="$HOME/Maildir"

#-------------------------------------------------------------------------
# Filter the mail with ClamAV
#-------------------------------------------------------------------------
exception {
    xfilter "/usr/bin/sanitizer /etc/sanitizer.cfg"
}

#-------------------------------------------------------------------------
# Filter the mail with SpamAssassin
# spamc automatically skip messages greater than 512000 bytes.
#-------------------------------------------------------------------------
if ($SIZE < 256000)
{
    exception {
        xfilter "/usr/bin/spamc"
    }
}

#-------------------------------------------------------------------------
# Move sender into a folder (beware of extra char in From header!).
#-------------------------------------------------------------------------
if (/^From: *Newsletter/)
{
    to Maildir/.News
}

#-------------------------------------------------------------------------
# Blackhole or move into subfolder messages tagged as SPAM.
#-------------------------------------------------------------------------
if (/^X-Spam-Flag: *YES/)
{
    exception {
        #to "/dev/null"
        # Create Spam subfolder (little overhead if it exists).
        #`${MAILDIRMAKE} -f Spam "$DEFAULT"`
        to "$HOME/Maildir/.Spam/"
    }
}