Royal Mail is to trial Sunday parcel deliveries for major retailers amid an online shopping boom.
Internet sales were already on the up before the coronavirus crisis, but the pandemic caused huge growth in 2020.
Royal Mail said the trial would open the door to parcel deliveries seven days a week.
The postal service has been hit by coronavirus delays, but a spokesperson said it was "working hard" to make deliveries.
Royal Mail said an increasing number of customers were shopping online and expected to get their purchases as soon as possible after placing their orders.
It said that "a number of retail brands are trialling the service" but declined to name them as yet.
Rivals such as DPD and Hermes already make Sunday deliveries for major retailers such as Amazon.
Nick Landon, chief commercial officer at Royal Mail, said: "The last year has reset so many customer expectations and the desire for even more convenient and even more frequent parcel deliveries has certainly been one of them."