They have rejected a pay offer of 5.5 percent.
Members of the CWU will walk out on Friday, August 26, Wednesday, August 31, Thursday, September 8, and Friday, September 9.
Royal Mail says it has ”well-developed contingency plans, but they cannot fully replace the daily efforts of its frontline workforce”.
No letters or packages, aside from those sent via Special Delivery, will be delivered on these dates.