A receptacle assembly is provided having a gasket interposed between a heat sink and the receptacle, in order to provide EMI shielding and limit leakage from an opening in the receptacle that allows the heat sink to engage an electronic module inserted in the receptacle cavity. The heat sink may have a groove in which the gasket is mounted and upon mounting the heat sink to the receptacle, the gasket surrounds the opening in the receptacle and provides a resilient shield to maintain a seal during movement of the heat sink due to insertion of the electronic module within the receptacle.