At the moment, Shipstation only allows 250 items per sales order (EOD manifest) with Royal Mail. This means that users cannot benefit from volume discounts provided by Royal Mail (as these orders need to be on the same sales order.
For example, I get a sales discount if I send out 400 orders per day, these will be split into 2 sales orders (of 250 and 150). I get a discount from Royal Mail for sending out 300 orders, but this will not be recognised, as neither sales order shows 300 orders.
There should be no upper limit on orders per sales order. As a comparison, Royal Mail's Click and Drop system does not have an upper limit
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