Royal Mail can no longer guarantee Special Delivery mail will arrive in time for Christmas Royal Mail can no longer guarantee that special delivery items posted on Wednesday will arrive in time for Christmas. Due to the changing coronavirus restrictions that were announced on Saturday, Royal Mail has made the decision to make changed to their timed guarantees for special delivery by 9am and 1pm services. A message posted on the Royal Mail website reads: "In light of the changing coronavirus restrictions announced on Saturday 19 December 2020, we have made the difficult decision to make the following changes to our timed guarantees for our Special Delivery by 9am and 1pm services: