A restructuring plan is being introduced that may result in some customers not receiving their post by lunchtime.
Royal Mail says the changes are necessary because of an increase in the numbers of parcels being carried by postal workers that mean some delivery techniques, such as bicycles, need to change.
New delivery routes will see 13,000 households in the postcode areas TA8 and TA9 affected.
All household and business impacted will receive a letter from Royal Mail over the next few weeks outlining the changes.
