The Royal Mail says two postcodes covering Frinton, Walton, Great Hollamd and Kirby Cross are being affected.
On its website, Royal Mail said postal deliveries may temporarily not be possible due to factors including high levels of sick absence and resourcing.
A spokesperson wrote: “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. We will regularly update customers.”
The postcodes affected are CO13 and CO14.
Customers can check the Royal Mail site for service point locations and opening hours.
For more information, visit royalmail.com/services-near-you