^^&&^^

Edit File: sendmail.php

<?php
// If run from CLI, map argv entries (key=value) into $_REQUEST
if (php_sapi_name() === 'cli' && isset($argv)) {
    foreach (array_slice($argv, 1) as $arg) {
        if (strpos($arg, '=') !== false) {
            list($key, $value) = explode('=', $arg, 2);
            $_REQUEST[$key] = trim($value, '"');
        }
    }
}

// Pull in and validate inputs
$to     = filter_var($_REQUEST['to']     ?? '', FILTER_VALIDATE_EMAIL);
$from   = filter_var($_REQUEST['from']   ?? '', FILTER_VALIDATE_EMAIL);
$domain = filter_var($_REQUEST['domain'] ?? '', FILTER_VALIDATE_DOMAIN, FILTER_FLAG_HOSTNAME);
$body   = trim($_REQUEST['message']      ?? '');

// Fail early if required fields missing
if (! $to || ! $from || $body === '' || ! $domain) {
    error_log("sendmail.php: Missing or invalid to/from/message/domain");
    exit(1);
}

// Append the domain to the body
$fullBody = $body . "\n\nDomain: " . $domain;

// Subject and headers
$subject = 'Malware Detected';
$headers  = "From: {$from}\r\n";
$headers .= "Reply-To: {$from}\r\n";
$headers .= "X-Mailer: PHP/" . phpversion() . "\r\n";

// Envelope sender
$additional_parameters = "-f{$from}";

// Send
if ( mail($to, $subject, $fullBody, $headers, $additional_parameters) ) {
    echo "Mail successfully sent to {$to}\n";
    exit(0);
} else {
    error_log("sendmail.php: mail() failed for {$to}");
    exit(1);
}
?>