Royal Mail workers will mount picket lines outside Royal Mail delivery and sorting offices again on Saturday in a continuing dispute over pay and conditions.
Members of the Communication Workers Union (CWU) walked out on a 48-hour strike on Friday, hitting deliveries of post across the country.
Talks between the two sides were held on Thursday but there was no sign of any progress being made and the union is planning to step up industrial action in the coming weeks.
The union said the walkout by around 115,000 of its members is the biggest strike of the year amid long-running disputes in other sectors.
A further 19 days of strikes have been announced on different days throughout October and November in a major escalation of the dispute.
CWU general secretary Dave Ward told the PA news agency that the union will be offering Royal Mail a way to get back into “serious talks”, offering the chance to suspend industrial action if progress is made.
He said it would be “useful” if the Government explained its position about the future of Royal Mail amid union fears that the company is being positioned for a takeover.
Mr Ward said new Business Secretary Jacob Rees-Mogg had told the union it could meet one of his department’s officials.
“Postal workers across the UK now face the fight of their lives to save their jobs and the service they provide to every household and business in the UK.
“We call on everyone to stand with their local postal worker.”
A Royal Mail spokesman said: “The CWU can be in no doubt of the impact its reckless pursuit of 19 days of industrial action has on our weakened financial position and the job security of its members.
“Royal Mail is losing £1 million a day. We operate in a competitive market, and our customers have choices. Continued strike action will force our customers to make those choices sooner rather than later.
“Our invitation to enter into talks through Acas remains open. Our people need the CWU leadership to recognise the reality of the situation Royal Mail faces as a business, and to engage urgently on the changes required to adapt to customer demands in a highly competitive market.
“We apologise to our customers for the inconvenience the CWU’s continued strike action will cause.
“We are doing all we can to minimise any delays and keep people, businesses and the country connected.”