At the top of the far right column on the late order report if you have a branch filter chosen you see labels that say 'check all' 'uncheck all' but if you don't have a filter nothing shows up there.
that is because we currently can only claim for one vendor at a time. So you select the orders to compose a letter to one vendor. The check/uncheck all show up once you have selected a vendor to filter on.
You can also compose a mail from the full list, but it will grey out all orders from other vendors, once you have selected the first order.