Office 2007 Delivery and Read Email Notisfication

When the sender has set up in their option to have the Delivery and Read
notification check and send the email, why isn't both notifications being
return to the sender after sending it to the recipient? The email address is
correct because the recipient has acknowledge they have the email verbally.
As well I know the option for these notifications is set up correctly because
I get the delivery report and read report from other recipients. Some I get
it from and some I don't. Is there a way I would know for sure if the
recipient did receive without asking always.
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2009 National Champs