That the message wasn't delivered. You'll need to provide more info than
this if you want a more specific answer. Most likely it is a misconfigured
mail server. Contact your mail admin or ISP.

Signature
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
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> What does "552 Backend Replied" mean in a returned failure notice mean?