Postal staff are said to have faced an hour round trip on private roads to the addresses in Altnabreac, Caithness.
Concerns for safety are linked to the fact the area has no phone signal, meaning no call for help could be made in difficulty.
A Royal Mail spokeswoman said: “We are sorry for the inconvenience this causes customers. Suspension of delivery is not something we do lightly, but we need to ensure that all our people are working in a safe environment.
“Ofcom’s own regulations state that postmen and women should not spend more than 15 minutes in a single trip on private roads to deliver mail.
“This step has been taken after a detailed assessment as we believe that there is a risk of safety to our postmen and women, who are delivering on private tracks off the public highway.
“Our people are spending an hour round trip to deliver the mail. There is also no mobile phone signal to call for help if there is an issue and the condition of the track is poor.”
Those staying at the properties can now either have their mail delivered to somewhere with the same postcode or make a round trip of about 36 miles to Halkirk.
The spokeswoman added none of those affected are housebound and have been collecting post from the delivery office in the village.