I don't think you can successfully mail frog or toad or any other amphibian eggs, for that matter. They are so delicate, and they hatch so quickly, you are inviting disaster.
Jerry, I have caught and transported to my pond quite a number of green tree frogs, and loved the sound of their calls - for about two nights. No matter how many I release here, and how many times I have done it, and how good a home I offer them, they always make their way to some other abode.