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How to determine whether an email address exists in php, php email address_PHP tutorial

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Jul 12, 2016 am 08:59 AM

phpexistemail address

php判断邮箱地址是否存在的方法，php邮箱地址

PHP校验邮箱地址的方法很多，比较常用的就是自己写正则了，不过正则多麻烦，我PHP自带了方法做校验。

filter_var

filter_var是PHP内置的一个变量过滤的方法，提供了很多实用的过滤器，可以用来校验整数、浮点数、邮箱、URL、MAC地址等。

具体的过滤器参考: filters.validate

filter_var如果返回false, 说明变量无法通过过滤器，也就是不合法了。

$email = "lastchiliarch@163.com";
 
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
 
 
$email = "asb";
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
 
$email = "1@a.com";
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
 
输出：
 
 
string(21) "lastchiliarch@163.com"
bool(false)
string(7) "1@a.com"

对于asb这种非法邮箱格式返回了false, 但对于1@a.com则通过了，还是略有瑕疵啊。

不过一般的正则也通过会认为1@a.com是一个合法的邮箱，那有啥办法可以更精准的验证呢？

checkdnsrr

checkdnsrr其实是用来查询指定的主机的DNS记录的，我们可以借用它来验证邮箱是否存在。

对于1@a.com肯定是MX记录不存在的。

$email = "lastchiliarch@163.com";
  var_dump(checkdnsrr(array_pop(explode("@",$email)),"MX"));
  $email = "1@a.com";
  var_dump(checkdnsrr(array_pop(explode("@",$email)),"MX"));
 
  输出:
  bool(true)
  bool(false)

可以看到，很完美，唯一的缺点就是太慢了，毕竟是要做一次网络请求。所以不适合同步对大量的邮箱采用这种做法去校验。

filter_var+checkdnsrr

我们可以接合filter_var 和checkdnsrr做校验，对于绝大多数的非法邮箱肯定会在filter_var的时候就挂掉了，剩下的再用

checkdnsrr进一步判断。

$email_arr = array("lastchiliarch@163.com", "1@a.com");
  foreach($email_arr as $email) {
    if (filter_var($email) === false) {
      echo "invalid email: $email \n";
      continue;
    }
 
    if(checkdnsrr(array_pop(explode("@",$email)),"MX") === false) {
      echo "invalid email: $email \n";
      continue;
    }
  }
 
  输出: invalid email: 1@a.com

但要注意的是，由于只是检查MX记录，所以只能判断163.com是存在的，但不能说明lastchiliarch这个用户是存在的。

想要更精确的判断邮箱存在，那只能连接到smtp服务器去验证了。

下面为大家分享的php邮箱地址正则表达式验证，具体内容如下

<&#63;php
 header ( "Content-Type: text/html; charset=UTF-8" );
 $reply = "";
 if ( isset($_POST["email_address"]) )
 {
  $email_address = $_POST["email_address"];
  $pattern = "/^([0-9A-Za-z\\-_\\.]+)@([0-9a-z]+\\.[a-z]{2,3}(\\.[a-z]{2})&#63;)$/i";
  if ( preg_match( $pattern, $email_address ) )
  {
   $reply = "您输入的电子邮件地址合法<br /><br />\n";
   $user_name = preg_replace( $pattern ,"$1", $email_address );
   $domain_name = preg_replace( $pattern ,"$2", $email_address );
   $reply .= "用户名：".$user_name."<br />\n";
   $reply .= "域名：".$domain_name."<br />\n\n";
  }
  else
  {
   $reply = "您输入的电子邮件地址不合法";
  }
 }
&#63;>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="zh" xml:lang="zh">
<head>
<title>电子邮件地址验证程序</title>
</head>
<body style="text-align: center;">
<h1 id="电子邮件地址验证程序">电子邮件地址验证程序</h1>
<form action="#" method="post">
请输入电子邮件地址：<input name="email_address" type="text" style="width: 300px;" /><br />
<input type="submit" value="验证电子邮件地址" />
</form>
<&#63;php
 echo $reply;
&#63;>
</body>
</html>

希望大家喜欢这篇文章，对大家有所帮助。

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