Total mail traffic has fallen by 40% since 2007
An Post recorded pre-tax losses of €15.6m in 2016 - the company says this reflects a global trend of mail decline.
Its total revenues came to €825.7m, that was in-line with the €826.1m earned in 2015 but the company's operating costs rose during the 12 months.
The total increase came to €18.4m and was "due to one-off costs and the impact of the Labour Court pay increase of 2.5%, costing €8.9m in 2016," according to the service provider.
In 2016 the total number of letters sent fell by 5.2% - total mail traffic has fallen by 40% since 2007.
An Post also notes that there is no evidence that its increase in stamp prices has had any impact on the number of letters being sent.
An Post faces a number of challenges. It is issuing fewer welfare payments as unemployment falls and it is handling a smaller number of cash transactions - such as the payment of bills - as these payments continue to move online.
The company is focusing on two new divisions to deliver growth - new finance offerings for retail businesses, and the area of parcel delivery services for online shoppers.
Chief Executive Officer, David McRedmond, who joined the Company in October 2016 said: "The results for 2016 show that the direction of travel for An Post needs to change. The digital world is closing one door with e-substitution of mails and online banking, while opening another into the world’s largest industry of shopping through e-commerce.
"We will price our services appropriately and deliver the best-in-class service in both our Mails and Post Office businesses for customers throughout Ireland. Parcel delivery will be at the core of what we do to ensure that a customer in Ballina has the same global access to goods as a customer in Boston or Barcelona," he added.