InterCD 2000 December/december_2000.iso/Intercd/root/Mail/^MailShield/setup.exe/data1.cab/Default_Rule_Files/rcptto.mml

Text File | 2000-10-18 | 5.6 KB | 157 lines

##############################################################################
# rcptto.mml
#
# MailShield script that is run after each SMTP RCPT TO: command
#

##############################################################################
# log this MAIL FROM message
#
#   &LogMessage("SMTP RCPT TO: '".$SmtpRcptTo."'");


##############################################################################
# Sleep for a few seconds if more than a certain number of recipients,
# for each recipient over that limit.  This prevents people who are allowed
# to relay through you from abusing that right and sending thousands
# of recipients through.

    if (scalar(@SmtpRcptTo) >= $slow_threshold) {
        &LogMessage("Waiting 2 seconds for recipient number: ".scalar(@SmtpRcptTo), "log_refuse");
        sleep(2);
    };


##############################################################################
# Sleep for a number of seconds if we have been instructed to tarpit this connection.

    if ($tarpit) {
        sleep($tarpit_delay);
    };


##############################################################################
# Check to see if this is a valid user on the destination server

    if ($chk_rcpt) {
        if (!&CheckRcptSmtpTcpip($SmtpRcptTo, $smtp_server)) {
            &Message("550 <".$SmtpRcptTo.">... no such user (reported by Mail Server)");
            $SmtpRcptTo = "";
            return;
        };
    };


##############################################################################
# Check to see if they are using a colon or percent sign to redirect the recipient

    if ((index($SmtpRcptTo, ":") > -1) || (index($SmtpRcptTo, "%") > -1) || (index($SmtpRcptTo, "!") > -1)) {
        &Message("550 : or % or ! redirected recipients are not allowed");
        $SmtpRcptTo = "";
        return;
    };


##############################################################################
# Check to see if more than one @ in the RCPT TO field

    @at_array = &extract(/\@/, $SmtpRcptTo);
    if (scalar(@at_array) > 1) {
        &Message("550 : Too many @ characters in destination address");
        $SmtpRcptTo = "";
        return;
    };


##############################################################################
# If this host has been accepted for relaying in begin.mml, the perform no more tests

    if ($accept) {
        exit;
    };

##############################################################################
# check for email addresses that we always accept mail to

    if (scalar(@ok_rcptto) > 0) {
        if (index(lc($SmtpRcptTo), @ok_rcptto) > -1) {
            $accept = TRUE;
            &MessageAppend(" (RCPT TO address approved for relaying)");
            exit;
        };
    };


##############################################################################
# Determine if the recipient is local or not, and refuse relaying if it is not
#
# Note: in begin.mml the connecting host is checked to see if they are
# allowed to relay mail, and if they are (at that point), the &Accept command
# is given to stop further checking. If, at this point, a non-local email
# address is specified as the recipient, then this is a relay request, and
# is refused.
#
# Note #2: if no local domains are specified in config.mml, then this test
# is skipped.

    if ($reject_relaying) {
        if ((index(lc($SmtpRcptTo), @local_domains) == -1) && (scalar(@local_domains) > 0)) {
            $smtp_message = "550 Relaying is not allowed";
            $log_message = "550 Relay request denied, and ".$SmtpRcptTo." is not a local domain name.";
            $relay_rejection = TRUE;
            &DefaultRejection;
        };
    };

##############################################################################
# check for email addresses that we do not accept mail to

    if (scalar(@no_rcptto) > 0) {
        if (index(lc($SmtpRcptTo), @no_rcptto) > -1) {
            $smtp_message = "550 Recipient refused.";
            $log_message = "550 Recipient is on banned RCPT TO list / matched ".$match;
            &DefaultRejection;
        };
    };


##############################################################################
# Check for maximum number of RCPT TO: allowed

    if (scalar(@SmtpRcptTo) >= $max_rcpt_to) {
        $smtp_message = "550 Too many recipients";
        $log_message = "550 Maximum number of recipients was exceeded. Maximum is ".$max_rcpt_to;
        &DefaultRejection;
    };


##############################################################################
# Do a gentle tarpitting if too many RCPT TO: are specified

    if ($tarpit_rcpt_to_threshold > 0) {
        if (scalar(@SmtpRcptTo) >= $tarpit_rcpt_to_threshold) {
            # the first time we start tarpitting RCPT TO, log it
            if ($first_time_tarpit_rcpt != 1) {
                $first_time_tarpit_rcpt = 1;
                &LogMessage("Tarpitting RCPT TO from host: ".$PeerHostname." [".$PeerTcpip."]", "log_refuse");
            };
            sleep(5);
        };
    };


##############################################################################
# Check for blank MAIL FROM and more than one recipient

    if ($onercpt) {
        if (length($SmtpMailFrom) == 0) {
            if (scalar(@SmtpRcptTo) > 1) {
                $smtp_message = "550 Message rejected";
                $log_message = "550 Message rejected because MAIL FROM was blank and more than 1 recipient was specified";
                &DefaultRejection;
            };
        };
    };