The Post Office said the majority of its branches were open despite the strike.
Three hundred branches are striking, but the Post Office said around 250 of these were open.
The rest of the Post Office's network of 11,600 branches is not involved in the dispute.
Post Office group network and sales director Kevin Gilliland said: "We want to reassure customers that nearly all of our network is unaffected by the strike action."
More top news
The fallout over the UK Government’s decision on Huawei and tributes to Nicholas Parsons lead many of Wednesday’s papers.
Wednesday will be a showery start for many western and northern parts with potentially some hail and thunder.
The roads have sections where the hard shoulder becomes a driving lane, leaving those who break down blocking traffic.