<script type="application/javascript">
(function($) {
$(document).ready(function() {

$(".et_social_icons_container").append('<li class="et_social_mail"><a href="mailto:someone@example.com" class="custom_button" rel="nofollow"><i class="et_social_icon et_social_icon_gmail"></i><span class="et_social_overlay"></span></a></li>');

});
})(jQuery)
</script>