Puppies, Kittens or Seals?

For the petition signup e-mail, the kitten appeal had a slightly higher open rate, but the clickthrough and action rates of the puppy e-mail were higher. But for the fundraising appeal — for which it used the same graphics, switching out "sign the petition" button with a "donate" button — the kitten e-mail outperformed the puppy e-mail, with a higher clickthrough rate, double the number of donors and more than double the amount raised.