Delivery routes in Maltby are being altered by Royal Mail.
Letters are now being sent to households and businesses to inform them of the changes, which are due to be introduced over the next few weeks.
Local elected representatives and business groups are also being advised of the changes.
A Royal Mail spokesman said: “Royal Mail is making some changes to the way it delivers mail in the S66 postcode areas.
“Postmen and women will use new delivery methods and adopt revised delivery routes as these changes are introduced.
“We are writing to every address in Maltby about these changes and this includes households, businesses and other organisations.
“The way in which we communicate with each other has changed dramatically.
“Unfortunately, fewer letters are now posted every day and Royal Mail needs to organise its delivery routes to be as efficient as possible.
“We also deliver more larger items and so are investing in new equipment to carry these items to customers even more securely.
“The new equipment also reduces the risk of injury to our postmen and women from carrying heavier mail bags.”
Royal Mail said staff will continue to deliver in the morning and many customers will continue to get their mail by lunchtime, but some may get theirs later than normal.
For details, call 0845 6011399.