Use the following function to validate the email address with valid domain.It returns TRUE on success and FALSE on failure.

Eg:
anbu_rajendran@yahoo.co.in is a valid email.

abc@abc.com is not a valid email.

/**************************************/

function email_validate($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;
}

/********************************/