The NPC required to sign up to Feedorama is found in Hummingberg, on a 2nd floor balcony of a peach-coloured house at the far right of the location. The NPC can only be found after you have acquired the double jump ability and have built a mailbox on your ship. It will cost 5000 glims to sign up for the recipe delivery service.
The 5th shipment will include a letter stating that management will be changing, and then you will receive a follow-up letter actually acknowledging the change of management. From this point on you will only receive letters containing bad food, simply labeled "Feedorama Delivery Package" with no numbering system. At this point you'll want to head back to the same NPC you originally signed up with and talk to them twice to get the option to unsubscribe from the delivery service for 10000 glims.
This will net you: