Post workers in two offices walked out last week over allegations of unfair sacking of their colleagues.
Some 150 delivery staff walked out of the Sindon office in Portsmouth at 7am on Wednesday of last week.
A worker of 15 years’ service had been asked to carry out more duties after finishing their shift. When they refused they were dismissed.
Management allege the worker threatened them.
Outraged staff gathered outside the site and demanded a review into managerial practices.
Bosses brought out workers’ belongings and said they were not welcome for the rest of the morning.
But the unofficial action forced Royal Mail to agree to a review, beginning from Tuesday of next week.
Workers went back into to the office at midday.
In Bridgwater, Somerset, workers walked out of Friarn St depot on Friday of last week over allegations a worker was sacked for taking sick leave.
The action involved 80 percent of the workforce.