<?PHP
/**
 * 验证邮件地址函数
 *
 * @param 
 * @arrange (512.笔记) jb51.cc
 **/
function validateEmail($email)
{
   $isValid = true;
   $atIndex = strrpos($email,"@");
   if (is_bool($atIndex) && !$atIndex)
   {
      $isValid = false;
   }
   else
   {
      $domain = substr($email,$atIndex+1);
      $local = substr($email,$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('/^"(\\\\"|[^"])+"$/',$local)))
         {
            $isValid = false;
         }
      }
      if ($isValid && !(checkdnsrr($domain,"MX") || checkdnsrr($domain,"A")))
      {
         // domain not found in DNS
         $isValid = false;
      }
   }
   return $isValid;
}


/***   来自编程之家 jb51.cc（jb51.cc）   ***/