Периодически приходит письмо - root@localhost Unrouteable address

Почта на сервере работает, почта отправляется и “получается”, но периодически приходит письмо от Mailer-Daemon, с текстом:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:

    Unrouteable address

------ This is a copy of the message, including all the headers. ------

Return-path: <[email protected]>
Received: from root by mydomen.kz with local (Exim 4.82)
	(envelope-from <[email protected]>)
	id 1W0I7C-0002md-HG
	for root@localhost; Tue, 07 Jan 2014 03:53:42 +0600

При этом ящик [email protected] существует и я с него могу отправлять и получать почту??