PHP 验证Email的函数

<?php

 

function validateEmail($email)

{

   $isValid = true;

   $atIndex = strrpos($email, "@");

   if (is_bool($atIndex) && !$atIndex)

   {

      $isValid = false;

   }

   else

   {

      $domain = substr($email, $atIndex+1);

      $local = substr($email, 0, $atIndex);

      $localLen = strlen($local);

      $domainLen = strlen($domain);

      if ($localLen < 1 || $localLen > 64)

      {

         // local part length exceeded

         $isValid = false;

      }

      else if ($domainLen < 1 || $domainLen > 255)

      {

         // domain part length exceeded

         $isValid = false;

      }

      else if ($local[0] == '.' || $local[$localLen-1] == '.')

      {

         // local part starts or ends with '.'

         $isValid = false;

      }

      else if (preg_match('/\\.\\./', $local))

      {

         // local part has two consecutive dots

         $isValid = false;

      }

      else if (!preg_match('/^[A-Za-z0-9\\-\\.]+$/', $domain))

      {

         // character not valid in domain part

         $isValid = false;

      }

      else if (preg_match('/\\.\\./', $domain))

      {

         // domain part has two consecutive dots

         $isValid = false;

      }

      else if

(!preg_match('/^(\\\\.|[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/',

                 str_replace("\\\\","",$local)))

      {

         // character not valid in local part unless

         // local part is quoted

         if (!preg_match('/^"(\\\\"|[^"])+"$/',

             str_replace("\\\\","",$local)))

         {

            $isValid = false;

         }

      }

      if ($isValid && !(checkdnsrr($domain,"MX") || checkdnsrr($domain,"A")))

      {

         // domain not found in DNS

         $isValid = false;

      }

   }

   return $isValid;

}

 

?>