如何来检测一个 email 地址？一般就需要从邮件地址的 smtp 服务器来获取一些信息来判断。
假设我要检测 testmail@douban.com 这个地址是不是真存在：
首先需要取得 douban.com 这个域的 MX 记录：
然后根据得到的 MX 地址来检测，用 telnet MX记录 端口号 来连接，然后输入命令：
从结果中基本可以看到 testmail@douban.com 这个地址返回的是 250 状态，是存在的；而下面的 jfksdjglfdgld@douban.com 则返回了 550 状态，同时也可以从下面的描述语句中得到这个地址则是不存在的。
下在的类就是根据上面的脚本写的一个 php 类，用来检测邮件地址是否真实存在。
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| <?php | |
| /** | |
| * 检测一个邮件地址是否真实存在 | |
| */ | |
| class verify_email { | |
| public $debug = FALSE; | |
| public $time_out = 30; | |
| public $host_name = 'localhost'; | |
| public $smtp_port = 25; | |
| public $log_str = ""; | |
| public $from = ''; | |
| public $sock; | |
| public function __construct($from = "", $smtp_port = 25) { | |
| $this->smtp_port = $smtp_port; | |
| $this->from = $from; | |
| $this->time_out = 30; //is used in fsockopen() | |
| $this->sock = FALSE; | |
| } | |
| public function check_mail($address) { | |
| $this->log_write("BEGINING CHECK address: ". $address . "\n"); | |
| if(!$this->is_email($address)) { | |
| $this->log_write("not an email address.\n"); | |
| return FALSE; | |
| } | |
| // | |
| if (TRUE !== $this->smtp_sockopen($address)) { | |
| return FALSE; | |
| } | |
| if (!$this->smtp_putcmd("HELO", $this->host_name)) { | |
| $this->log_write("sending HELO command\n"); | |
| return FALSE; | |
| } | |
| if (!$this->smtp_putcmd("MAIL", "FROM:<" . $this->from . ">")) { | |
| $this->log_write("sending MAIL FROM command\n"); | |
| return FALSE; | |
| } | |
| if (!$this->smtp_putcmd("RCPT", "TO:<" . $address . ">")) { | |
| $this->log_write("sending MAIL TO command\n"); | |
| return FALSE; | |
| } | |
| return TRUE; | |
| } | |
| private function is_email($address) { | |
| return preg_match("/^[0-9a-zA-Z]+@(([0-9a-zA-Z]+)[.])+[a-z]{2,4}$/i",$address); | |
| } | |
| private function smtp_sockopen($address) { | |
| return $this->smtp_sockopen_mx($address); | |
| } | |
| private function smtp_sockopen_mx($address) { | |
| $domain = preg_replace("/^.+@([^@]+)$/i", "$1", $address); | |
| if (!@getmxrr($domain, $MXHOSTS)) { | |
| $this->log_write("Error: Cannot resolve MX \"" . $domain . "\"\n"); | |
| return FALSE; | |
| } | |
| foreach ($MXHOSTS as $host) { | |
| $this->log_write("Trying to " . $host . ":" . $this->smtp_port . "\n"); | |
| $this->sock = @fsockopen($host, $this->smtp_port, $errno, $errstr, $this->time_out); | |
| if (!($this->sock && $this->smtp_ok())) { | |
| $this->log_write("Warning: Cannot connect to mx host " . $host . "\n"); | |
| $this->log_write("Error: " . $errstr . " (" . $errno . ")\n"); | |
| continue; | |
| } | |
| $this->log_write("Connected to mx host " . $host . "\n"); | |
| return TRUE; | |
| } | |
| $this->log_write("Error: Cannot connect to any mx hosts (" . implode(", ", $MXHOSTS) . ")\n"); | |
| return FALSE; | |
| } | |
| private function smtp_putcmd($cmd, $arg = "") { | |
| if ($arg != "") { | |
| if ($cmd == "") | |
| $cmd = $arg; | |
| else | |
| $cmd = $cmd . " " . $arg; | |
| } | |
| fputs($this->sock, $cmd . "\r\n"); | |
| $this->smtp_debug("> " . $cmd . "\n"); | |
| return $this->smtp_ok(); | |
| } | |
| private function smtp_ok() { | |
| $response = str_replace("\r\n", "", fgets($this->sock, 512)); | |
| $this->smtp_debug($response . "\n\n"); | |
| if (!ereg("^[23]", $response)) { | |
| fputs($this->sock, "QUIT\r\n"); | |
| fgets($this->sock, 512); | |
| $this->log_write("Error: Remote host returned \"" . $response . "\"\n"); | |
| return FALSE; | |
| } | |
| return TRUE; | |
| } | |
| private function log_write($str) { | |
| $this->log_str .= $str; | |
| } | |
| public function get_log() { | |
| $str = $this->log_str; | |
| $this->log_str = ''; | |
| return $str; | |
| } | |
| private function smtp_debug($message) { | |
| if ($this->debug) { | |
| echo $message; | |
| } | |
| } | |
| } | |
| // Testing | |
| $newemail = "doubanjgdl@kfdkldfg@163.com"; | |
| $randval = substr(md5(uniqid(rand())), 0, 6); | |
| $verifyEmail = new verify_email($randval . "@mailtest.com"); | |
| echo $newemail . ' is '; | |
| if (TRUE === $verifyEmail->check_mail($newemail)) { | |
| echo "OK\n"; | |
| } else { | |
| echo "BAD\n"; | |
| } | |
| //echo $verifyEmail->get_log(); |
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