troubleshooting Question

Customer is getting errors e-mailing our domain and it seems to bypass spam filter

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SlagwagFlag for United States of America asked on
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We have an Exchange 2010 environment utilizing Postini for incoming e-mail. Our mail server is configured to only allow incoming e-mail from Postini so it has to get filtered rather then hitting our server directly. However one customer sending us e-mail cannot get through and gets the following e-mail back:

From: []
Sent: Friday, February 03, 2012 12:16 PM
To: Customer Name
Subject: failure notice

This is the mail delivery agent at
I was not able to deliver your message to the following addresses.

Connected to but sender was rejected.
Remote host said: 530 5.7.1 Client was not authenticated

Is messagelabs spam filtering somehow sending to us directly?

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