Before sending up your FBA inventory for the the first time there are a number of setting which must be specified in Settings > Fulfilment by Amazon.
Cross border fulfilment settings.
Pan European FBA is a programme where listings can be delivered across Europe at the delivery rate of the ordering country. To qualify a listing must have a listing in each of the EU4 (FR, DE, IT, ES) and Enable multi-country inventory storage.
To be accepted into Amazon warehouses, some product must have a new Amazon specific barcode affixed (Amazon Barcode). Choose whether to allow Amazon to apply new barcodes where they are necessary. This incurs a fee per label.
Choose what warning to see when sending up FBA inventory. Some product may be fine to sell on Amazon but can’t be sent to FBA.
Enabling Furblishing allows Amazon to inspect items and put them back into inventory if possible
Removal settings specific what to do with unfulfillable items (e.g. return or destroy)
Chose to use the manufacturer’s barcode or a new barcode for each product. If the manufacturer’s barcode is used then Amazon will use this identify items and these can be commingled with the exact same products from other sellers who also use Manufacturer barcodes for those items. That is to say if you make a sale of a product then that same product as supplied by another seller may be sent.
This is usually fine, but some unscrupulous sellers have been known to send up fakes.
Selecting to use Amazon barcodes means that your product will be sent to fulfil your orders, but items must be individually re-barcoded using codes specified by Amazon.
More details can be found here: https://sellercentral.amazon.co.uk/gp/help/help.html?itemID=G200141480&language=en_GB
Specify whether to allow Amazon to manage customer service for your orders
Shipping programmes and export settings
Chose whether to allow overseas customers to purchase your FBA products.