I would let the user know what was going on and then tell them what happened. So, tell them when it is sent, and then tell them when it was sent.
Same:
$(".sendEmail").click(function(){
var element = $(this);
var guest_id = element.attr("id");
element.replaceWith('Sending...');
$.post("WebGuest_SendEmail.php",{id: guest_id}, function(data) {
$(this).html(data);
element.replaceWith('Sent!');
});
return false;
});
, , , if, - script. , , ..