Post office customers in Douglas and Ramsey are being promised current services will continue - when town centre business is transferred to the Spar retail chain.
Flagship post offices in Regent Street in Douglas and Parliament Street in Ramsey are due to close early next year.
Sub post offices will be opened in nearby high street Spar stores in both towns, with all existing services maintained.
The posts of 19 staff are to close, but job opportunities will be available at the new outlets.
Mannin Retail which runs Spar stores in the Isle of Man has pledged to offer an extensive, high quality service.
The firm's managing director Peter Whittacker says the new arrangement has much to offer.
A computer-generated walk-through of floor plans for Ramsey and Douglas can be viewed on You Tube via a link on the Isle of Man Post Office website.