Glow or Emit from behind opaque material texture/mesh

I have a cube with a material on it. I have put some “holes” in it in random places in photoshop, exposing the transparent background. I would like to have the cube emit a glow but only have it come through the transparent “holes” on the material. Is this possible and if so, how?

I tried setting an emitter with a red glow, but the whole cube glows, material and all.

Make an emission mask texture and assign it in the material. White areas on the texture would mean 100% emission and black would be 0% emission with gray values in between.

If you are on PC, add a full screen post process effect… this will add glow and fuzzy “bloom” to all of the bright areas on the screen. as long as you render your “holes” with the bright color (bright emissive on the holes), you’ll get nice glow that will even bleed out above the surface of the cube when viewed from a shallow angle.
UNity has built in bloom (in ‘post process stack’), or many on the asset store also.