We address the regularity of the solution to the time dependent Maxwell equations of electromagnetics in the case of metallic boundary condition under minimal regularity of the data. We extend the so-called extractor technique that we introduced in 1995 for wave equation in several cases (including the non-cylindrical case of moving domains for which the sharp-hidden regularity  was still an open problem). Concerning the electrical vector field we consider its normal component
at the boundary and, using a specific version of the so called pseudo-differential extractor (that we recently introduced in a different context), we obtain new sharp regularity results that are quantified in terms of curvature through the
oriented distance function
and all the intrinsic geometry we developed in the book .