Система доставки почты и ошибка GMAIL

После изучения следующего урока:

http://blog.seeit.org/2010/08/php-mail-with-ubuntu-desktop-and-gmail/ [ 113]

для отправки электронной почты через Gmail.

Я получаю следующую ошибку:

Mail Delivery System MAILER-DAEMON@

12:38 AM (20 hours ago)

to me
This is the mail system at host .

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

               The mail system

<root@smartlab.cs.ucy.ac.cy> (expanded from <"root@domain>):
delivery temporarily suspended: connect to
domain[IP]: No route to host

Final-Recipient: rfc822; root@domain
Original-Recipient: rfc822;root@domain
Action: failed
Status: 4.4.1
Diagnostic-Code: X-Postfix; delivery temporarily suspended: connect to
domain[IP]: No route to host


---------- Forwarded message ----------
From: root <username@gmail.com>
To: root
Cc: 
Date: Mon, 30 Jul 2012 00:20:01 +0300
Subject: Cron <smmsp@machine> test -x /etc/init.d/sendmail &&    /usr/share/sendmail/sendmail cron-msp
/usr/share/sendmail/sendmail: 1267: /usr/sbin/sendmail-msp: not found

Кто-нибудь знает, как это исправить?