An Post is to introduce zero-emission postal deliveries in Dublin city centre by the end of the year, with plans to extend the service to Cork, Galway, Limerick, Kilkenny and Waterford by the end of 2020.
The company has placed an order for 200 electric vehicles that will operate on all deliveries between the Grand Canal and Royal Canal by the end of year.
Speaking on RTÉ's News at One, the chief executive of An Post said it is essential that the company move to zero-emissions vehicles.
David McRedmond said that by the end of 2020, 750 of the company's 2,750-strong fleet will be electric.
He said the only major obstacle to expanding the plan to the five other cities named is "getting the vehicles into the country".
He also said the vehicles were necessary as due to the changing nature of An Post's service, they are delivering a lot more parcels.
"You can't do that with bicycles, so we need to bring in more vehicles," he said.
Mr McRedmond said the change will not affect deliveries in these areas, saying they would be charged overnight at sorting offices to ensure they have enough power for the day's deliveries.
However, he admitted that electrifying the company's rural fleet is a greater challenge.
"We have to wait for technology to catch up to do the longer rural routes," he said.
He added that the company are looking at installing charging points at or near post offices around the country, in addition to those being rolled out by the ESB.
In the interim, he said drivers of existing diesel vehicles would continue to receive "eco training" to reduce emissions.