Sorting office employees are back at work following an unballotted strike.
People living in the PE6 postal area had their normal deliveries disrupted after about 200 staff at the Werrington sorting office in Peterborough walked out on Friday.
This included the Deepings, Helpston, Baston, West Deeping and the towns and villages in between.
The PE1, PE2, PE3, PE4 and PE5 postcodes were also affected.
But staff returned to work on Tuesday.
Peterborough branch chairman of the Communication Workers Union Andy Beeby said there had been a disciplinary issue early on Friday and meetings were being held between union officials and management.
A Royal Mail spokesman apologised to customers for any delays to deliveries.