  Several extensions of the Standard Model predict the existence of sub-GeV
particles that can be copiously produced in the cores of supernovae. A broad
family of these particles are dubbed feebly interacting particles (FIPs), which
can have masses of up to a few hundreds of MeV. Here, we review the most recent
and leading constraints on electrophilic FIPs, describing multimessenger
techniques that allow us to probe the full phenomenology of the
electron/positron emission produced by these FIPs; from their associated X-ray
emission to the production of the $511$~keV line. Furthermore, the approach
described here is independent of the specific particle model and can be
translated to the coupling and other properties of a variety of different
particles, such as axion-like particles, sterile neutrinos or dark photons
