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According to Dublin Airport web information, the airlines which fly from Terminal 2 are Aer Lingus, American Airlines, Delta, Emirates, and United. Your onward flight to the US would have to be with one of those carriers to take advantage of its pre-clearance services.
US Preclearance at Dublin Airport
The US Preclearance (USCBP) facility at Terminal 2 in Dublin Airport is a purpose built facility that allows US bound passengers to undertake all US immigration, customs and agriculture inspections at Dublin Airport prior to departure.
Dublin Airport is one of only a handful of airports outside North America that offers a US Preclearance facility. The benefit is that having cleared USCBP, passengers arriving in the US are treated as domestic arrivals, allowing them to avoid immigration queues upon arrival and pick up their bags and go.
In addition, this benefits onward connecting passengers in the US who will have their baggage checked through to their final destination.