The postal workers union is stepping up its campaign to protect the daily delivery service on one of the busiest days of the year for its members.
The Communication Workers Union is urging the public to show support for their postie and help preserve the universal service of deliveries to 29 million homes and businesses.
Labour leader Jeremy Corbyn is set to join a group of postal workers in London, while a senior CWU official will go out on a delivery round.
CWU general secretary Dave Ward said: "National Postal Workers Day - traditionally the busiest posting day of the year - is your chance to give posties across the UK the recognition they deserve. The CWU is campaigning hard to protect the terms and conditions of our members at the same time as preserving the service that we provide to the public and businesses. Royal Mail may have been sold off on the cheap, but the service is and always will be the people's post."
Deputy general secretary Terry Pullinger, who will deliver post today, said: "Postal Workers Day is an opportunity to acknowledge the hard work our members do. They also serve our communities in other ways, doing amazing things beyond the call of duty.
"Royal Mail is the only postal service that can connect with each of the 29 million addresses in the UK six days a week, every week, at a guaranteed uniform price to anywhere in the country for less than the cost of a cup of coffee. This is an amazing human and logistical effort, which too many of us take for granted."
CWU reps and members across the UK will be posting photos to social media using #PeoplesPost and the union is calling on the public and businesses to join in.