We present silver-epoxy filters combining excellent microwave attenuation with efficient wire thermalization, suitable for low temperature quantum transport experiments. Upon minimizing parasitic capacitances, the attenuation reaches ≥100 dB above ≈150 MHz and—when capacitors are added—already above ≈30 MHz. We measure the device electron temperature with a GaAs quantum dot and demonstrate excellent filter performance. Upon improving the sample holder and adding a second filtering stage, we obtain electron temperatures as low as 7.5 ± 0.2 mK in metallic Coulomb blockade thermometers.