I am not able to find the FedEx SmartPost service under FedEx integration anymore.


This has happened because FedEx SmartPost® service has been renamed to FedEx Ground® Economy. There are some additional options for Indicia Type, which you can edit in > Shipping > Integrations > FedEx > Services > Edit screen.

You can choose options such as 'Media Mail', 'Bound Printed Matter', 'Returns', 'Under 1lb' and 'Parcel Select'.

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FedEx: How to Edit Services