Enterprise Minister Fergus Ewing has written to UK retailers asking them how they intend to promote new guidelines that state consumers living in rural areas should not be discriminated against.
The code was developed by the Parcel Delivery Working Group, established last year by the watchdog Consumer Futures and the Scottish Government.
Agreed by industry, trading standards and consumer groups, it urges businesses to avoid charging disproportionate delivery costs and provide the widest possible delivery coverage.
Mr Ewing said: "Although the principles are voluntary, we believe they will help to support businesses and reduce the number of customers who abandon purchases at the last minute because they find out the cost of delivery.
"It is not acceptable to hear reports of customers in the Highlands and Islands experiencing excessive charges, being refused delivery and being misled by the term 'free delivery'.
He added that he would encourage retailers to take on board these guidelines so that customers, particularly in the Highlands and Islands, receive a fairer service.
Online retailers, by their adoption of these guidelines, would be showing respect for their customers, he said.
Trisha McAuley, Scottish director at Consumer Futures, said: "The new principles are a good example of different sectors working together to identify best practice in delivery services."