I don't think sending pictures of dead animals is necessarily the best way to educate people. I would send that pyramid that shows how many cats come from one feral mamma in a short time...that's a bit more profound and civilized.

If you are concerned for the animals your friends and family have, why don't you educate them personally. You can even research low cost spay/neuter clinics and let them know how inexpensive it can be.