cannot send email from hotmail to google app email

Email contains error messages got from hotmail:

From: postmaster@mail.hotmail.com
To: kkk@hotmail.com
Date: Fri, 15 Jun 2012 20:39:46 -0700
Subject: Delivery Status Notification (Failure)

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

       xxx@yyy.zzz


Reporting-MTA: dns;col0-omc1-s10.col0.hotmail.com
Received-From-MTA: dns;COL107-W41
Arrival-Date: Fri, 15 Jun 2012 20:39:36 -0700

Final-Recipient: rfc822;xxx@yyy.zzz
Action: failed
Status: 5.7.1
Diagnostic-Code: smtp;554 5.7.1 <xxx@yyy.zzz>: Relay access denied

It is because hotmail server tries to send email through yyy.zzz server which is not the email server (google's). Actually, hotmail should find address of email server by asking for MX record from the domain yyy.zzz instead.

http://productforums.google.com/forum/#!category-topic/apps/mail-settings/Yd0JG0jRn7M