Depending on your Duet Scenarios, you may experience issues with the size of your Duet Request Handler's mailbox size, such as exceeding the limits setup by your Exchange Administrator. The Request Handler account is responsible for sending the messages from Duet to your clients. The Reporting and Analytics scenario is a good example where you could see this issue very quickly. If your Duet system is sending out an average of 200 reports that are two megabytes in size during a day to clients, the mailbox can exceed 400 MB. If your Exchange Administrator has setup limits on the mailbox of 250 megabytes, your Request Handler may no longer be able to send out reports. To avoid this issue, the Request Handler now offers a configuration option so that it will not store the sent items.
If you have implemented the Duet 1.5 Service Pack 1 (http://support.microsoft.com/?kbid=961122) or later for the Request Handler Service, you now have the option to not keep the sent items in the Request Handler's mailbox. Saving items in the sent items folder is the default option for the Request Handler, so you must manually perform the steps below after the installation to avoid saving items. To set this option:
The Duet Request Handler should no longer be saving sent items.
Original post: http://blogs.technet.com/duet/archive/2009/06/02/new-duet-1-5-request-handler-configuration-option.aspx