Scattering of light by a strong electric field is called Delbrueck
scattering. It is observable when a photon scatters from the field
of an atomic nucleus. See Jauch and Rohrlich, "The Theory of Photons
and Electrons", section 15-8. In terms of Feynman diagrams, the
incoming photon splits into an electron-positron pair, which must
interact with the static field not once but twice (or more), then
recombine to form the outgoing photon. What we call a "photon", you
see, is really a seething bundle of virtual particles, including
electron-positron pairs that can be deflected by an electromagnetic
field.