Postal services will begin returning to normal today after the Communications Workers' Union (CWU) suspended industrial action by its members in An Post.
The company advised customers last night to resume posting mail, but warned of likely delays in deliveries over the coming days.
The union's national overtime ban and strike at the GPO in Dublin lasted just 18 hours, ending at 6pm following a meeting of its disputes committee.
The committee acceded to a request by the National Implementation Body (NIB) that the action be deferred pending an independent examination of costs in dispute between the parties.
The CWU wants changes in four areas to a Labour Court recommendation issued in July on major work practice changes required by An Post in its collection and delivery service.
Forensics accountant Paul Jacobs, of the firm Grant Thornton, was appointed by the NIB yesterday to examine how much it would cost the company to accede to the union's demands. He is to issue a report by next Monday to the NIB.
The NIB, which met both sides for five days in succession last week, will then decide how the issues in dispute should be addressed. It could convene further talks between the parties or refer certain matters back to the Labour Court. In any event, an early resumption of industrial action is unlikely.
But the two sides continued to trade insults yesterday, suggesting a permanent resolution of the dispute will be difficult to achieve.
An Post said any delays in deliveries in the coming days were "a result of the unnecessary, irresponsible and damaging industrial action taken by the CWU, their failure to avert the action on Sunday and the lateness of their announcement of a final decision to cease the disruption".
CWU general secretary Steve Fitzpatrick criticised the company for advising customers not to post mail yesterday.
"This over-eagerness by the company to shut down the national postal service confirms the union's long-held belief that management are intent on wreaking havoc and destroying the national postal service."
It is understood the NIB asked the two parties last night to tone down their public criticisms of each other.
The action by the CWU's 8,500 members is over the company's refusal to pay the full terms of Sustaining Progress. The Labour Court recommended that the increases be linked to the work practice changes in collection and delivery. This was accepted by An Post but rejected by the union.