Postal workers are going ahead with a planned 24-hour strike in a row over pay cuts and job losses.
The Communication Workers Union (CWU) industrial action the third taken in a fortnight will see Royal Mail employees walk out at 19:00 BST.
Union bosses announcing the industrial action last week said the strike was entirely preventable, calling on Royal Mail chairman Allan Leighton to personally intervene in talks aimed at avoiding further disruption.
But despite fresh talks between the two parties last night, the CWU revealed the strike would go ahead as planned.
"Disappointingly, Royal Mail simply concentrated on reiterating their previous offer that the workforce has already overwhelmingly rejected," the union said.
On its part Royal Mail insists its modernisation drive is essential to ensuring the firm can compete with other delivery firms operating in the UK.
A spokesman said the company was "hugely disappointed" at the latest strike action, and admitted that despite "well-developed" contingency plans, disruption on the network was "inevitable".
"Further strike action will achieve nothing," Royal Mail said previously. "The union is saying nothing new and is simply ignoring the challenge confronting everyone in Royal Mail which is the absolute need to modernise as all our major our rivals have already done to reduce our costs in order to ensure we can compete successfully in an increasingly tough market.
"Strike action only makes it even tougher for Royal Mail to secure its future and continue to provide great quality of service for its customers."
The initial CWU strike held on June 29th was the first 24-hour walkout by postal workers for a decade.