Each time I try to use ShipRush.

Due to the security settings in Outlook, the maximum amount of time you can set is 10 minutes. After 10 minutes, you will need to acknowledge the prompt the next time you want to do a shipment.

There is a utility out there that automatically clicks the "Yes" button for you in the background, so you no longer need to.

Please go to: http://www.contextmagic.com/express-clickyes/

The item is freeware and very simple to install.