Picket lines were mounted outside Royal Mail offices on the sixth day of action in recent months including outside the Sun Street depot in Wolverhampton and the delivery office in Market Drayton.
The Communication Workers Union (CWU) said its 115,000 members across the UK joined the latest stoppage, describing it as the largest strike in a year that has seen industrial unrest across several industries, including rail.
The union accused Royal Mail of planning structural change, which would effectively see employees in secure, well-paid jobs turned into a “casualised, financially precarious workforce overnight”.
The CWU said plans include delaying the arrival of post to members of the public by three hours, cuts in workers’ sick pay and inferior terms for new employees.
The union has announced 19 further days of strike action in the coming weeks.
At the Sun Street depot in Wolverhampton, the union members were in full voice and good spirits as they began another day of protests, with support from passing motorists who honked their car horns.
Wolverhampton CWU branch chair Andy Morris said there had been a good showing at the picket line and said the strike action had been gaining some ground.
He said: "Today's strike action is relating to pay and we still maintain that we would like a reasonable pay rise, one which rewards us for all the work we've done.
"The shareholders and bosses have all received good bonuses and the members feel that the two per cent that was imposed on them was not in line with inflation and was not reasonable in terms of rewarding us for the work we've done, particularly during the pandemic.
"There has been an impact from the strike action, as the CEO Simon Thompson is now in negotiations with the national team and I think there is a glimmer of hope that there is some movement on this now."
General secretary Dave Ward said: “Postal workers face the biggest ever assault on their jobs, terms and conditions in the history of Royal Mail.
“The public and businesses also face the end of daily deliveries and destruction of the special relationship that postal workers and the public have in every community in the UK.
“It is insulting the intelligence of every postal worker for Royal Mail chief executive Simon Thompson to claim that their change agenda is ‘modernisation’.
“It is nothing more than an asset-stripping business plan that will see the break-up of the company and the end of Royal Mail as a major contributor to the UK economy.
“Royal Mail Group claim to be losing £1 million a day. The CWU believe these figures need to be scrutinised.”
A Royal Mail spokesman said: “Three weeks ago, Royal Mail invited the CWU to enter talks through Acas to find a resolution to our change and pay dispute. We have not reached an agreement with the CWU on this request.
“Royal Mail is losing £1 million a day and must change faster in response to changing customer demands.
“The CWU leadership’s choice of damaging strike action over resolution is weakening the financial position of the company and threatening the job security of our postmen and women.
“We call on the CWU leaders to cancel their planned strike action and accept our invitation to enter talks through Acas without further delay.
“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.”