Catalyzes the reduction of bound ferric iron (Fe(3+)) in a variety of iron chelators (siderophores) using NAD(P)H as the electron donor, resulting in the release of Fe(2+). Not active with uncomplexed Fe(3+). Also reduces FMN and FAD, but not riboflavin. 2 a Fe(II)-siderophore + H(+) + NAD(+) = 2 a Fe(III)-siderophore + NADH 2 a Fe(II)-siderophore + H(+) + NADP(+) = 2 a Fe(III)-siderophore + NADPH Optimum temperature is 88 degrees Celsius. Homodimer. Belongs to the non-flavoprotein flavin reductase family.