APIPA IP address in email tracking log when using Exchange 2010 DAG

One of our customers noticed a strange thing when investigating a tracking log for an email in Exchange 2010. The user that was sending the email had his mailbox hosted on a database member of a DAG. Instead of seeing the IP address of the DAG or mailbox server, it was a an APIPA address like:

Received: from ex1.testdomain.com (169.254.50.10) by ex2.testdomain.com (10.50.1.5) with Microsoft SMTP Server (TLS) id 14.2.247.3; Thu, 12 Jan 2012 17:21:53 +0200

Googling the issue I found this article http://technet.microsoft.com/en-us/magazine/gg314976.aspx from TechNet Magazine. The problem is generated by the Windows Failover Cluster (WFC) component that is installed and configured automatically when you configure an Exchange 2010 DAG.

If that IP address bothers you, please read the above article.