SmtpFailedRecipientsException does not throw on Email exception

I've attempted to run the example Email exception code below through Exchange but, the SmtpFailedRecipientsException does now throw.
http://msdn.microsoft.com/en-us/library/system.net.mail.smtpfailedrecipientsexception.aspx 
However, I do receive an email stating that the email is undeliverable because of an invalid email address.  Is there a way to make the application throw the exception properly?
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