Hassocks Royal Mail postal delivery office is to relocate to Burgess Hill this summer.
The move follows discussions with the Communication Workers Union and Royal Mail staff in both offices.
Bosses say there will be no impact on postal deliveries to customers and that there will be no job losses because of the switch.
They say that the move is part of Royal Mail’s ongoing transformation of its business to increase efficiency as well as providing delivery offices which are ‘fit for purpose.’
A spokesman said: “As a commercial business, Royal Mail is responding to the huge growth in electronic communications and decline in letter volumes, while seeing a high volume of parcels and online shopping which need to be delivered to customers.
“Detailed planning is now underway to help ensure a smooth transition for our operations, our people and the service we provide to our customers.”
He added: “If customers choose to collect mail from us because they were not at home when we tried to deliver it, they will be able to do this from the customer service point at Burgess Hill delivery office. This is open considerably longer than the office at Hassocks, including until 8pm on Wednesdays.
“Hassocks customers do not have to travel to Burgess Hill to pick up their mail if they do not want to or are unable to do so. Royal Mail can now leave many mail items with a neighbour if customers are not at home when we attempt delivery. Customers can nominate a dedicated neighbour to take in their parcels by filling in a form at their delivery office.
“Customers can also arrange a redelivery free of charge on a day that is convenient for them - including Saturdays - or Royal Mail can deliver the item to a different address within the same postcode area.
“This service can be arranged by calling the number on the ‘Something for You’ card we leave or by visiting our website at www.royalmail.com/redelivery.”