直接上代码：

<?php
$array_values['host'] = "host";
$array_values['port'] = 110;
$array_values['user'] = '用户名';
$array_values['password'] = '密码';
$array_values['checkmail'] = 'xxx@xxx.xxx';

ganji_get_test_mail($array_values);

function ganji_get_test_mail($array_values)
{
  $host = $array_values['host'];
  $port = $array_values['port'];
  $user = $array_values['user'];
  $password = $array_values['password'];
  $checkmail = $array_values['checkmail'];
  $msg = '';
  $return_msg = '';
  // ini_set('memory_limit', '80M');
  if (! ($sock = fsockopen(gethostbyname($host), $port, $errno, $errstr))) {
    exit($errno . ': ' . $errstr);
  }

  set_socket_blocking($sock, true);

  $command = "USER " . $user . "\\r\\n";
  fwrite($sock, $command);
  $msg = fgets($sock);
  $command = "PASS " . $password . "\\r\\n";
  fwrite($sock, $command);
  $msg = fgets($sock);

  $command = "stat\\r\\n";
  fwrite($sock, $command);
  $return_msg = fgets($sock);

  $msg = fgets($sock);

  $command = "LIST\\r\\n";
  fwrite($sock, $command);
  $all_mails = array();
  while (true) {
    $msg = fgets($sock);
    if (! preg_match('/^\\+OK/', $msg) && ! preg_match('/^\\./', $msg)) {
      $msg = preg_replace('/\\ .*\\r\\n/', '', $msg);
      array_push($all_mails, $msg);
    }
    if (preg_match('/^\\./', $msg))
      break;
  }

  // 获取邮件列表
  $ganji_mails = array();
  foreach ($all_mails as $item) {
    fwrite($sock, "TOP $item 0\\r\\n");
    while (true) {
      $msg = fgets($sock);
      // echo $msg . "<Br><Br>";
      if (preg_match('/^\\./', $msg)) {
        array_push($ganji_mails, $item);
        break;
      }
    }
    continue;
  }

  $mail_content = '';
  $array_ganji_mails = array();

  //逐行遍历
  foreach ($ganji_mails as $item) {
    fwrite($sock, "RETR $item\\r\\n");
    while (true) {
      $msg = fgets($sock);
      $mail_content .= $msg;
      if (preg_match('/^\\./', $msg)) {
        array_push($array_ganji_mails, iconv_mime_decode_headers($mail_content, 0, "UTF-8"));
        $mail_content = '';
        break;
      }
    }
  }

  // 直接获取第一封邮件全部信息 9999长度
  fwrite($sock, "RETR 1\\r\\n");
  $mail_contents = fread($sock, 9999); // 直接获取全部

  echo "<br>";
  var_dump($mail_contents);
  echo "<br>";

  $command = "QUIT\\r\\n";
  fwrite($sock, $command);
  $msg = fgets($sock);

  return $mail_contents;
}

常用的POP3命令介绍　：

命令参数状态描述USERusername认可此命令与下面的pass命令若成功，将导致状态转换PASSpassword　认可
APOPName,Digest认可Digest是MD5消息摘要STATNone处理请求服务器发回关于邮箱的统计资料，如邮件总数和总字节数UIDL[Msg#]处理返回邮件的唯一标识符，POP3会话的每个标识符都将是唯一的LIST[Msg#]处理返回邮件数量和每个邮件的大小RETR[Msg#]处理返回由参数标识的邮件的全部文本DELE[Msg#]处理服务器将由参数标识的邮件标记为删除，由quit命令执行RSETNone处理服务器将重置所有标记为删除的邮件，用于撤消DELE命令TOP[Msg#] 处理服务器将返回由参数标识的邮件前n行内容，n必须是正整数NOOPNone处理服务器返回一个肯定的响应，不做任何操作。QUITNone更新退出

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