#! /usr/bin/php
  <?php
  // include shared code
  include '../lib/config.php';
  include '../lib/db.php';
  include '../lib/POP3Client.php';
  
  // establish a connection to the POP3 server
  $pop\; =\; new\; POP3Client();$pop->connect(POP3_SERVER, POP3_PORT);
  $pop->user(MANAGE\_USER)$pop->pass(MANAGE_PASSWORD);
  
  // process each message in inbox
  foreach (array_keys($pop->\_list())\; as$id)
  {
      // fetch message
      $message\; =$pop->retr($id);$// retrieve the email address and subject headers
      preg_match_all('/From: (.+)|Subject: (.+)/i', message, $matches);$from = trim($matches[1][0]);$subject = trim($matches[2][1]);$// determine if the email address exists
      query = sprintf('SELECT EMAIL_ADDR FROM \%sMAILLIST_USER WHERE ' .
          'EMAIL_ADDR = "\%s"', DB_TBL_PREFIX,
          mysql_real_escape_string($from,$GLOBALS['DB']));
      $result\; =\; mysql\_query($query, $GLOBALS[\text{'}DB\text{'}]);$exists = (mysql_num_rows($result));\; mysql\_free\_result($result);
  
      // send appropriate response
      switch (strtoupper($subject))\; \{$// subscribe email address to list
          case 'SUBSCRIBE':
              if (exists)
              {
                  // address already exists
                  $response\_file\; =\; \text{'}already\_subscribed.txt\text{'};\; \}\; else\; \{$query = sprintf('INSERT INTO \%sMAILLIST_USER ' .
                      '(EMAIL_ADDR) VALUES ("\%s")', DB_TBL_PREFIX,
                      mysql_real_escape_string($from,$GLOBALS['DB']));
  
                  $response\_file\; =\; (mysql\_query($query, $GLOBALS[\text{'}DB\text{'}]))\; ?\; \text{'}subscribe.txt\text{'}\; :\; \text{'}error.txt\text{'};\; \}\; break;$// remove email address from list
          case 'UNSUBSCRIBE':
              if (exists)
              {
                  $query\; =\; sprintf(\text{'}DELETE\; FROM$\%sMAILLIST_USER WHERE ' .
                      'EMAIL_ADDR = "\%s"', DB_TBL_PREFIX,
                      mysql_real_escape_string(from, $GLOBALS[\text{'}DB\text{'}]));$response_file = (mysql_query($query,$GLOBALS['DB'])) ?
                      'unsubscribe.txt' : 'error.txt';
              }
              else
              {
                  // address does not exist
                  $response\_file\; =\; \text{'}not\_subscribed.txt\text{'};\; \}\; break;$// set preference for digest
          case 'SET +DIGEST':
              if (exists)
              {
                  $query\; =\; sprintf(\text{'}UPDATE$\%sMAILLIST_USER SET ' .
                      'IS_DIGEST = 1 WHERE EMAIL_ADDR = "\%s"', DB_TBL_PREFIX,
                      mysql_real_escape_string(from, $GLOBALS[\text{'}DB\text{'}]));$response_file = (mysql_query($query,$GLOBALS['DB'])) ?
                      'digest_on.txt' : 'error.txt';
              }
              else
              {
                  // address does not exist
                  $response\_file\; =\; \text{'}not\_subscribed.txt\text{'};\; \}\; break;$// set preference for individual messages
          case 'SET -DIGEST':
              if (exists)
              {
                  $query\; =\; sprintf(\text{'}UPDATE$\%sMAILLIST_USER SET ' .
                      'IS_DIGEST = 0 WHERE EMAIL_ADDR = "\%s"', DB_TBL_PREFIX,
                      mysql_real_escape_string(from, $GLOBALS[\text{'}DB\text{'}]));$response_file = (mysql_query($query,$GLOBALS['DB'])) ?
                      'digest_off.txt' : 'error.txt';
              }
              else
              {
                  // address does not exist
                  $response\_file\; =\; \text{'}not\_subscribed.txt\text{'};\; \}\; break;$// use help message
          case 'HELP':
              response_file = 'help.txt';
  
          // unknown command was received
          default:
              $response\_file\; =\; \text{'}unknown.txt\text{'};\; \}$// Read the data
      response = file_get_contents(REPLY_DIR . '/' . $response\_file);$// these placeholders will be swapped in the message templates
      replace = array('<list_email>' => LIST_EMAIL,
                       '<manage_email>' => MANAGE_EMAIL);
      $response\; =\; str\_replace(array\_keys($replace), array_values($replace),$response);
  
      // send message
      mail($from,\; \text{'}RE:\; \text{'}\; .$subject, $response,\; \text{'}From:\; \text{'}\; .\; LIST\_EMAIL\; .\; "\backslash r\backslash n"\; .\; \text{'}Reply-To:\; \text{'}\; .\; LIST\_EMAIL\; .\; "\backslash r\backslash n");$// mark message for delete
      pop->dele($id);\; \}$pop->quit();
  mysql_close($GLOBALS[\text{'}DB\text{'}]);\; ?>$