Some of the fields in ShippingEasy are not mapped correctly to the Amazon store order feed. For example there is a field called buyer-company-name which should be mapped to the field company in ShippingEasy but currently the field is returned as null and the company name is mapped to address2

Also the ShippingEasy fields sales_channel and fulfillment_channel are null, not sure why instead of having Amazon filled out

There are also other important fields that should be mapped such as

purchase-order-number
latest-delivery-date

Purchase order number should be included as part of the shipping label or a reference number. The latest delivery date is a good guide to know when an order will be late

Optional fields that should be also mapped can include

delivery-Instructions

Delivery instructions are good to know in case the delivery address must have certain notes added

For ShippingEasy to be completely flexible for all the users, it will be better if you provide custom mapping. We had a previous service that allowed this, at setup it will display all the columns available from the Feed and allow a drop-down menu to selected a Field to map it to. This way users can map information that is useful for their shipping needs/business practices. At least being able to map fields not currently available to custom_1,2,3 would be very useful.