Post workers in Weston-Super-Mare in Somerset were set to strike on Thursday of this week.
Workers are furious over heavy workloads and allegations of bullying management.
The strike comes after workers in the CWU union requested further walkouts at a meeting. It affects 140 workers at the Royal Mail depot in Warne Road.
Some 130 workers walked out in August this year—for the first time in 20 years.
A CWU spokesperson said workers are “incensed” at how bosses are treating them. “There will be further strike action unless Royal Mail agrees to reconvene talks,” he added.