The $210 million (£146.75 million) US court action against An Post has been dropped, following a settlement between the State company and the US firm, Escher.
An Post said last night it had relinquished all property rights to Riposte, the software programme whose ownership was at the centre of the dispute.
Under the settlement terms, An Post will receive "an agreed residual licence fee revenue stream" from sales of the current version of the software.
A spokesman for the State company would not say how much this was likely to be worth.
An Post, which relies on the programme to deliver thousands of pension and social welfare payments each day, will also have the right to use the most up-to-date version of Riposte for the next 10 years, and Escher will continue to use An Post as a demonstration site.
The settlement leaves Escher free to sell the software around the world; the US firm has said it aims to make Riposte the global industry standard. The post offices of Germany, Britain, Denmark, Austria, Slovakia and Singapore have already purchased the programme.
