Royal Mail and the CWU are due to resume talks at the conciliation service Acas on Monday against a backdrop of bitterness over the continuing dispute.
Planned strikes by Royal Mail workers over the next two weeks have been called off following an apparent legal challenge by the company.
The Communications Workers Union (CWU) said on Sunday it had withdrawn walkouts due on 2, 3, 4, 8, 9 and 10 November.
They had been due to form part of its continuing dispute over pay and conditions, which includes opposition to the company's modernisation plans.
Talks aimed at resolving the row are due to resume at the conciliation service Acas later on Monday but the divisions, on the surface, seem just as wide in the wake of Royal Mail's legal intervention.
The CWU said its decision to withdraw the strike notices had stoked deep frustration among its 115,000 members at the company.
Acting deputy general secretary Andy Furey said: "We entirely understand the anger felt by many over the decision but we believe it is a necessary move to protect our dispute.
"Our members have been facing down serious harassment from the highest levels of Royal Mail as they defend their industry and those communities they serve.
"They will not be forced into submission so easily, and we will be reminding the company of their determination at Acas in the coming days."
The company is holding off union demands for pay rises that would shield staff from the cost of living crisis.
It is demanding an element of a pay rise be linked to modernisation plans, including Sunday parcel deliveries, and has already revealed plans for up to 6,000 redundancies next year.
It has warned the redundancy figure will have to rise if strike action persists.
Royal Mail said in a statement: "The CWU has withdrawn strike action following Royal Mail writing to CWU to highlight numerous material concerns with the formal notification of planned rolling strike action."
It added: "We will continue to do all we can to keep business, companies and the country connected."