I had been thinking about this task for the longest time!
Everytime I get a message from our email system they always get a delivery receipt confirming that my blackberry had received their email.
I know how annoying it is to get lots of unnecessary junk email so finally I decided to look for the solution.
I googled the term “blackberry how to disable delivery receipt” and got this results.
http://www.berryreview.com/2007/12/19/how-to-enabledisable-delivery-read-receipts/
I think its fixed now.