Near mass shell singularities in quantum electrodynamics

We discuss the near mass shell infrared behavior of QED by performing an explicit sum over all Feynman diagrams in the eikonal approximation. We review the infrared singularities of exclusive amplitudes in particular limits ((a) small photon mass or dimension ≠ 4, (b) equal off shell p_i², (c) large momentum transfers) as special cases of a general parametric formula. In the parametric representation the infrared singularities always exponentiate. This allows us to derive simple differential equations for Laplace transforms of the scattering amplitudes. Similar differential equations have been conjectured to hold in QCD and we summarize the present evidence regarding this assumption.