// COPY UND PASTE 
function clear_field(field) {
    if (field.value == "Ihre@E-Mail") {
        field.value = "";
    }
}
function paste_field(field) {
    if (field.name == "email" && field.value == "") {
        field.value = "Ihre@E-Mail";
    }
}
// END: COPY UND PASTE