Pelo que pesquisei achei apenas duas funcoes um para validar o email e
outra para validar o servidor ai montei algo, simples
<?
class ValidateMail{
	
	
	/**
	*@param string $email
	*@param string $record
	*return bool
	*/
	public static function DOMAIN_EXIST($email,$record = 'MX'){
		
		if(!self::EMAIL_VALID($email) )
			return false;
			
			list($user,$domain) = split('@',$email);
			return checkdnsrr($domain,$record);
		
	}
	
	/**
	*@param type string $email
	*return bool
	*
	*/
	public static function EMAIL_VALID($email){
		
		$conta    = "^[a-zA-Z0-9\._-]+@";  		
		$domino   = "[a-zA-Z0-9\._-]+.";  		
		$extensao = "([a-zA-Z]{2,4})$";		
		$pattern  = $conta.$domino.$extensao;  		
		
		return ereg($pattern, $email);
			
	}
	
}
/**
*@implementacao
*include 'ValidateMail.php';
*ValidateMail::DOMAIN_EXIST($email)
*ira retornar TRUE or FALSE
*/
?>
2009/12/3 Stephan A. de Souza <
bla...@gmail.com>: