From an arts business in Caithness to a building company on Arran, an estimated 15,000 firms are having to deal with punitive extra fees.
Tales of people living in rural areas paying over the odds for items arriving by courier are well known, but Citizens Advice Scotland (CAS) has published new research showing the impact of the unfair charges on commercial life.
Some 90% of the near 250 businesses who responded to a CAS survey reported they are charged extra for having items delivered just because of their postcode and 76% felt this had a substantial impact on their business.
About eight out of 10 regularly encountered misleading claims of "free delivery", when surcharges were actually imposed due to their location.
A majority of sellers were also unwilling or unable to depart from their standard carrier arrangements.
Meanwhile, more than three-quarters of the Scottish respondents were regularly classed as "offshore" or "remote" when ordering items online. This included businesses whose premises were on the Scottish mainland but were considered an island.
One example is the world-renowned Three Chimneys Restaurant on Skye. Shirley Spear the co-owner said: "We are linked to the UK mainland by a one-mile-long road bridge, but still regarded as off-shore.
"I object when anywhere from Cornwall to John O'Groats is considered 'normal' but the Skye Bridge sets us off-limits."
She said that being charged high delivery charges was "grossly unfair" and said the issue was "a constant headache and one which affects us every single day and has added considerably to the cost of every major development project we have undertaken over 30 years. Unfair. Never taken seriously as an issue."
Len Ford has a construction business in Inveraray. He said: "I was telephoned with regard to a problem with an order for a glass hearth. My order had been accepted but was told there would be an extra delivery charge of £19 + vat.
"When I asked to send it by small packet Royal Mail, I was told that they were not set up to do this. They also said that the charges were beyond their control."
Keith Dryburgh, Citizens Advice Scotland's policy manager, said the Postcode Penalty: the Business Burden report showed it was a problem across Scotland, not just the Highlands and Islands.
He said: "What we have found is that businesses across Scotland are very badly hit by this problem, and it is a serious burden on them."
Most of the respondents were from the north and north east but the survey revealed the issue was not confined to rural areas. It also affects major urban areas as well.
Mr Dryburgh said: "We have found in previous research that many companies base their delivery fees purely on postcodes, rather than on the actual cost of delivering an item.
"Mark-ups can be as much as 50%, which can be devastating to a small business which has to buy in stock."
Among CAS's recommendations are that wherever possible, retailers should offer delivery by Royal Mail and if delivery by Royal Mail is not possible, retailers should give customers a clear reason why this is the case.
Sellers and carriers should offer alternative points as options for delivery, working in conjunction with the Post Office and local community hubs such as shops to facilitate this.