West Kirby and Hoylake are among dozens of hotspots around the country where mail deliveries are being delayed due to Covid-19.
The sorting office at Hoylake, as well as Upton and Wallasey, are named on a list of sites where there are delays because staff are isolating or off sick.
It is affecting postal deliveries in postcode areas CH47 and CH48, as well as CH27, CH30, CH39 and CH44.
Royal Mail has apologised and said it is “rotating deliveries to minimise the delay”.
A statement on its website states: “We aim to deliver to all addresses we have mail for, six days a week.
“In a small number of local offices this may temporarily not be possible due to local issues such as COVID-related self isolation, high levels of sick absence, resourcing, or other local factors. In those cases we will rotate deliveries to minimise the delay to individual customers.
“We also provide targeted support to those offices to address their challenges and restore our service to the high standard our customers would normally receive.
“We’re sorry for any inconvenience and thank you for your understanding.”
A full list of the areas affected can be found at https://personal.help.royalmail.com/app/answers/detail/a_id/12556/~/service-update