inspect-mail/inspect-mail.php

<?php

//ini_set('max_execution_time', 0);
//ini_set('memory_limit', -1);
error_reporting(0);

if ( ! $_POST['domain'] ) {
	echo '<span style="color: red;">Mail Server field is empty.</span>';
	die;
}

echo '<br><form action="inspect-mail.php" method="post">
	  	<input type="text" name="domain" value="' . $_POST['domain'] . '">
        <input type="submit" value="ReTest">
      </form>
      <p><em>Note: To get NS and MX records for the domain, make sure you test a FQDN that has a valid A record. domain.tld should work.<br>
      To get SPF record, test SMTP server\'s FQDN with a valid A record or it\'s IP address.</em><br></p>';

//  Identify, set data and report info
if ( filter_var( $_POST['domain'] , FILTER_VALIDATE_IP ) ) {
    $isIP = true;
} else {
    $isIP = false;
}

if ( $isIP ) {
    $ip =   $_POST['domain'];
    $host = $ip;
} else {
    $host = strtolower( $_POST['domain'] );
    $ip =   gethostbyname( $host );

  	// Get nameservers for the domain
    $dns =      dns_get_record( $host , DNS_NS );

    // Get MX for the domain
    $dnsmx =    dns_get_record( $host , DNS_MX );

    // Get SPF for the domain
    $dnstxt =   dns_get_record( $host , DNS_TXT );

  	// Die if Cloud Flare domain
	if ( $dns ) {
    	foreach ( array_reverse( $dns ) as $ns ) {
        	if ( strpos( $ns['target'] , 'cloudflare.com' ) !== false ) {
            	echo '<span style="color: red;">This is a Cloud Flare domain. Data can\'t be collected for this domain.</span>';
              	die;
            }
        }
    }

    if ( $ip == $host ) {
        echo '<span style="color: red;">IP address has not been found for the given domain name.</span><br>';
        die;
    } else {
        echo '<h2>Domain Info</h2><strong>Domain:</strong> ' . $host .'<br><strong>IP address:</strong> ' . $ip . '<br>';
    }

    // Print nameservers for the domain
    if ( $dns ) {
        echo '<h2>Name Server</h2>';
        foreach ( array_reverse( $dns ) as $ns ) {
            echo $ns['target'] . '<br>';
        }
    }

    // Print MX for the domain
    if ( $dnsmx ) {
        echo '<h2>MX record</h2>';
        foreach ( array_reverse( $dnsmx ) as $nmx ) {
            echo $nmx['target'] . '<br>';
        }
    }

    // Print SPF for the domain
    if ( $dnstxt ) {
        echo '<h2>SPF record</h2>';
        foreach ( $dnstxt as $ntxt ) {
            if ( strpos( $ntxt['txt'], 'v=spf1' ) !== false ) {
                if ( strpos( $ntxt['txt'], $ip ) !== false ) {
                    echo '<span style="color: green;">' . $ntxt['txt'] . '</span><br>';
                } elseif ( strpos( $ntxt['txt'], '.' . $host ) !== false ) {
                    echo '<span style="color: darkorange;">' . $ntxt['txt'] . '</span><br>';
                } elseif ( strpos( $ntxt['txt'], $host ) !== false ) {
                    echo '<span style="color: green;">' . $ntxt['txt'] . '</span><br>';
                } else {
                    echo '<span style="color: red;">' . $ntxt['txt'] . '</span><br>';
                }
            }
        }
    }
}

// Print PTR for an IP
echo '<h2>PTR record the IP address</h2>';
echo '<em>Note: No valid PTR record will be retrieved for the IP address of the server that is hosting this script.</em><br><br>';

$ptr = gethostbyaddr( $ip );
if ( ! $ptr || $ptr == $ip ) {
	echo '<span style="color: red;">No PTR record found.</span>';
} elseif ( $ptr == $host ) {
	echo '<span style="color: green;">' . $ptr . '</span>';
} elseif ( strpos( $ptr, $host ) !== false ) {
	echo '<span style="color: darkorange;">' . $ptr . '</span>';
} elseif ( $isIP ) {
	echo $ptr;
} else {
	echo '<span style="color: red;">' . $ptr . '</span>';
}

// Ports
$ports = array( 25, 110, 143, 465, 587, 993, 995 );

// Non SSL ports
$nonssl = array( 25, 110, 143 );

echo '<h2>Mail Ports</h2>';
foreach ( $ports as $port ) {
    $connection = @fsockopen( $host, $port, $errno, $errstr, 1 );
    if ( is_resource( $connection ) ) {
        echo '<h3 style="color: green;">' . $host . ': ' . $port . ' (' . getservbyport( $port, 'tcp' ) . ') is open.</h3>';
        fclose( $connection );
    } else {
        echo '<h3 style="color: red;">' . $host . ': ' . $port . ' is not responding.</h3>';
        $nonssl[] = $port;
    }
}

// Removing closed ports
$sslports = array_diff( $ports, $nonssl );

if ( count( $sslports ) != 0 ) { 
    echo '<h2>SSL Cert on Ports</h2>';
}

foreach ( $sslports as $sslport ) {
	$url =              "tcp://" . $host;
	$orignal_parse =    parse_url( $url, PHP_URL_HOST );
    $get =              stream_context_create(array( 
                            "ssl" => array(
                                'capture_peer_cert' => true, 
                                'verify_peer' => false, 
                                'verify_peer_name' => false ) ) );
	$read =             stream_socket_client( "ssl://" . $orignal_parse . ":" . $sslport, $errno, $errstr, 1, STREAM_CLIENT_CONNECT, $get );
	$cert =             stream_context_get_params( $read );
	$certinfo =         openssl_x509_parse( $cert['options']['ssl']['peer_certificate'] );

    // Print cert data
  	echo '<h3>Certificate on port: ' . $sslport . '</h3>';
	if ( ! empty( $certinfo['subject']['CN'] ) ) {
            if ( $certinfo['subject']['CN'] == $host ) {
                echo '<strong>Common Name:</strong> <span style="color: green;">' . $certinfo['subject']['CN'] . '</span><br>';
            } else {
                echo '<strong>Common Name:</strong> <span style="color: darkorange;">' . $certinfo['subject']['CN'] . '</span><br>';
            }
        echo '<strong>Issuer:</strong> ' . $certinfo['issuer']['CN'] . '<br>';
        echo '<strong>Valid From:</strong> ' . gmdate( 'r', $certinfo['validFrom_time_t'] ) . '<br>';
    	if ( strtotime( $certinfo['validTo_time_t'] ) > time() ) {
            echo '<strong>Valid To:</strong> <span style="color: red;">' . gmdate( 'r', $certinfo['validTo_time_t'] ) . '</span>';
        } else {
            echo '<strong>Valid To:</strong> <span style="color: green;">' . gmdate( 'r', $certinfo['validTo_time_t'] ) . '</span>';
        }
	}
  	else {
    	echo '<span style="color: red;">There is no certificate on the port.</span>';
    }
}