diff --git a/humbug/urls.py b/humbug/urls.py
index fcbda639d9..28e52761e3 100644
--- a/humbug/urls.py
+++ b/humbug/urls.py
@@ -19,7 +19,8 @@ urlpatterns = patterns('',
     url(r'^subscriptions/manage/$', 'zephyr.views.manage_subscriptions', name='manage_subscriptions'),
     url(r'^subscriptions/add/$', 'zephyr.views.add_subscriptions', name='add_subscriptions'),
     url(r'^static/(?P<path>.*)$', 'django.views.static.serve',
-        {'document_root': os.path.join(settings.SITE_ROOT, '..', 'zephyr', 'static/')})
+        {'document_root': os.path.join(settings.SITE_ROOT, '..', 'zephyr', 'static/')}),
+    url(r'^subscriptions/exists/(?P<zephyr_class>.*)$', 'zephyr.views.class_exists', name='class_exists'),
 
     # Uncomment the admin/doc line below to enable admin documentation:
     # url(r'^admin/doc/', include('django.contrib.admindocs.urls')),
diff --git a/templates/zephyr/index.html b/templates/zephyr/index.html
index 885513b5ce..25732dbdac 100644
--- a/templates/zephyr/index.html
+++ b/templates/zephyr/index.html
@@ -51,6 +51,16 @@ var people_list = {{ people }};
     </ul>
 
     <div class="tab-content">
+        <div class="alert" id="class-dne">
+            <p>The class <span class="classname" id="class-dne-name"></span> does not exist.</p>
+            <a id="create-it" class="btn btn-primary" href="#">Create and send</a>
+            <a class="btn" onClick="$('#class-dne').stop(true).fadeOut(500);">Cancel message</a>
+        </div>
+        <div class="alert" id="class-nosub">
+            <p>You're not subscribed to the class <span class="classname" id="class-nosub-name"></span>.</p>
+            <a id="sub-it" class="btn btn-primary" href="#">Subscribe and send</a>
+            <a class="btn" onClick="$('#class-nosub').stop(true).fadeOut(500);">Cancel message</a>
+        </div>
         <div class="tab-pane active" id="class-message">
             <form action="/zephyr/" method="post" class="zephyr">
                 <input type="hidden" name="type" value="class" />
diff --git a/zephyr/static/js/zephyr.js b/zephyr/static/js/zephyr.js
index 8dacf901ff..e4035c604e 100644
--- a/zephyr/static/js/zephyr.js
+++ b/zephyr/static/js/zephyr.js
@@ -42,6 +42,12 @@ $.ajaxSetup({
      }
 });
 
+function sub(zephyr_class) {
+    // Supports multiple classes, separate by commas.
+    // TODO: check the return value and handle an error condition
+    $.post('/subscriptions/add/', {new_subscriptions: zephyr_class});
+}
+
 $(function() {
     var status_classes = 'alert-error alert-success alert-info';
     var send_status = $('#send-status');
@@ -56,6 +62,42 @@ $(function() {
                        .stop(true).fadeTo(0,1);
             buttons.attr('disabled', 'disabled');
             buttons.blur()
+            var okay = true;
+            $.ajaxSetup({async:false}); // so we get blocking gets
+            $.get("subscriptions/exists/" + $("#class").val(), function(data) {
+                if (data == "False") {
+                    // The class doesn't exist
+                    okay = false;
+                    send_status.removeClass(status_classes)
+                    send_status.toggle();
+                    $('#class-dne-name').text($("#class").val());
+                    $('#class-dne').show();
+                    $('#create-it').focus()
+                                   .click(function() {
+                        sub($("#class").val());
+                        $("#class-message form").ajaxSubmit();
+                        $('#class-dne').stop(true).fadeOut(500);
+                                   });
+                    buttons.removeAttr('disabled');
+                }
+            });
+            $.ajaxSetup({async:true});
+            if (okay && class_list.indexOf($("#class").val()) == -1) {
+                // You're not subbed to the class
+                okay = false;
+                send_status.removeClass(status_classes);
+                send_status.toggle();
+                $('#class-nosub-name').text($("#class").val());
+                $('#class-nosub').show();
+                $('#sub-it').focus()
+                            .click(function() {
+                        sub($("#class").val());
+                        $("#class-message form").ajaxSubmit();
+                        $('#class-nosub').stop(true).fadeOut(500);
+                            });
+                buttons.removeAttr('disabled');
+            }
+            return okay;
         },
         success: function (resp, statusText, xhr, form) {
             form.find('textarea').val('');
diff --git a/zephyr/static/styles/zephyr.css b/zephyr/static/styles/zephyr.css
index 06c66f711d..f61dcd5ab7 100644
--- a/zephyr/static/styles/zephyr.css
+++ b/zephyr/static/styles/zephyr.css
@@ -90,6 +90,18 @@ form.zephyr textarea {
     display: none;
 }
 
+#class-dne {
+    display: none;
+}
+
+#class-nosub {
+    display: none;
+}
+
+span.classname {
+    font-weight: bold;
+}
+
 #connection-error .alert {
     margin-bottom: auto;
 }
diff --git a/zephyr/views.py b/zephyr/views.py
index dd10574196..778d16501a 100644
--- a/zephyr/views.py
+++ b/zephyr/views.py
@@ -20,6 +20,13 @@ import datetime
 import simplejson
 import socket
 
+def require_post(view_func):
+    def _wrapped_view_func(request, *args, **kwargs):
+        if request.method != "POST":
+            return HttpResponseBadRequest('This form can only be submitted by POST.')
+        return view_func(request, *args, **kwargs)
+    return _wrapped_view_func
+
 def json_response(res_type="success", msg="", status=200):
     return HttpResponse(content=simplejson.dumps({"result":res_type, "msg":msg}),
                         mimetype='application/json', status=status)
@@ -95,10 +102,8 @@ def home(request):
                               context_instance=RequestContext(request))
 
 @login_required
+@require_post
 def update(request):
-    if not request.POST:
-        # Do something
-        pass
     user = request.user
     user_profile = UserProfile.objects.get(user=user)
     if request.POST.get('pointer'):
@@ -107,11 +112,8 @@ def update(request):
     return json_success()
 
 @asynchronous
+@require_post
 def get_updates_longpoll(request, handler):
-    if not request.POST:
-        # TODO: Do something
-        pass
-
     last_received = request.POST.get('last_received')
     if not last_received:
         # TODO: return error?
@@ -132,11 +134,8 @@ def get_updates_longpoll(request, handler):
     user_profile.add_callback(handler.async_callback(on_receive), last_received)
 
 @login_required
+@require_post
 def zephyr(request):
-    if not request.POST:
-        # TODO: Do something
-        pass
-
     user_profile = UserProfile.objects.get(user=request.user)
     zephyr_type = request.POST["type"]
     if zephyr_type == 'class':
@@ -262,3 +261,7 @@ def add_subscriptions(request):
             new_subscription.save()
 
     return HttpResponseRedirect(reverse('zephyr.views.subscriptions'))
+
+@login_required
+def class_exists(request, zephyr_class):
+    return HttpResponse(bool(ZephyrClass.objects.filter(name=zephyr_class)))