diff --git a/admin/views.py b/admin/views.py
index 88427ae15..e70b52516 100644
--- a/admin/views.py
+++ b/admin/views.py
@@ -574,7 +574,7 @@ def edit_domain_admin(request, da_id, tplname="admin/adminform.html"):
 
 @login_required
 @permission_required("auth.view_permissions")
-def domain_admin_promotion(request):
+def domain_admin_promotion(request, tplname="admin/domain_admin_promotion.html"):
     if request.method == "POST":
         form = DomainAdminPromotionForm(request.POST)
         if form.is_valid():
@@ -590,9 +590,10 @@ def domain_admin_promotion(request):
             messages.info(request, _("Domain admin added"), fail_silently=True)
             return ajax_response(request, url=reverse(admin.views.permissions))
 
+        return ajax_response(request, status="ko", template=tplname, form=form)
+
     form = DomainAdminPromotionForm()
-    return ajax_response(request, template="admin/domain_admin_promotion.html",
-                         form=form)
+    return ajax_response(request, template=tplname, form=form)
 
 @login_required
 @permission_required("auth.view_permissions")
diff --git a/extensions/postfix_autoreply/templates/postfix_autoreply/autoreply.html b/extensions/postfix_autoreply/templates/postfix_autoreply/autoreply.html
index 7f8790c35..c7a9a6fe2 100644
--- a/extensions/postfix_autoreply/templates/postfix_autoreply/autoreply.html
+++ b/extensions/postfix_autoreply/templates/postfix_autoreply/autoreply.html
@@ -16,8 +16,9 @@
 <script type="text/javascript">
 window.addEvent("domready", function() {
   var cal = new Calendar({id_untildate: "Y-m-d"}, {tweak: {x: -100, y:-100}});
+  var form = new Form();
 
-  register_error_callback("armform", function() {
+  form.register_error_callback("armform", function() {
     new Calendar({id_untildate: "Y-m-d"}, {
       tweak: {x: -100, y:-100}
     });
diff --git a/extensions/sievefilters/templates/sievefilters/filter.html b/extensions/sievefilters/templates/sievefilters/filter.html
index 2e2217be1..0ff1c30c6 100644
--- a/extensions/sievefilters/templates/sievefilters/filter.html
+++ b/extensions/sievefilters/templates/sievefilters/filter.html
@@ -42,6 +42,8 @@ function initform() {
 }
 
 $(document).addEvent("domready", function() {
+  var form = new Form();
+
   new Request.JSON({
     url: "{% url modoboa.extensions.sievefilters.views.get_templates 'condition' %}",
     onSuccess: function(response) {
@@ -55,8 +57,8 @@ $(document).addEvent("domready", function() {
       initform();
     }
   }).get();
-  register_error_callback("filterform", initform);
-  register_extra_data_callback("filterform", function() {
+  form.register_error_callback("filterform", initform);
+  form.register_extra_data_callback("filterform", function() {
     return "conds=" + dc.fields_cnt + "&actions=" + da.fields_cnt;
   });
 });
diff --git a/extensions/sievefilters/templates/sievefilters/newfiltersset.html b/extensions/sievefilters/templates/sievefilters/newfiltersset.html
index f9de4181e..134c60d77 100644
--- a/extensions/sievefilters/templates/sievefilters/newfiltersset.html
+++ b/extensions/sievefilters/templates/sievefilters/newfiltersset.html
@@ -5,23 +5,25 @@
 <script src="{{ MEDIA_URL }}js/form.js" type="text/javascript"></script>
 <script type="text/javascript">
 $(document).addEvent("domready", function() {
-  register_success_callback("newfiltersset", function(response) {
-    var name = response.url;
-    var option = new Element("option", {value: name, html: name});
-    var curfset = $(parent.document).getElementById("curfset");
+    var form = new Form();
 
-    option.inject(curfset);
-    curfset.set("value", name);
-    if ($("id_active").checked) {
-      curfset.getElements("option").each(function(item) {
-        if (item.get("value") == name) {
-          item.set("html", name + " (" + gettext("active") + ")");
-        } else {
-          item.set("html", item.get("value"));
+    form.register_success_callback("newfiltersset", function(response) {
+        var name = response.url;
+        var option = new Element("option", {value: name, html: name});
+        var curfset = $(parent.document).getElementById("curfset");
+
+        option.inject(curfset);
+        curfset.set("value", name);
+        if ($("id_active").checked) {
+            curfset.getElements("option").each(function(item) {
+                if (item.get("value") == name) {
+                    item.set("html", name + " (" + gettext("active") + ")");
+                } else {
+                    item.set("html", item.get("value"));
+                }
+            });
         }
-      });
-    }
-  });
+    });
 });
 
 </script>
@@ -29,7 +31,8 @@ $(document).addEvent("domready", function() {
 {% block content %}
 <div class="title"><h1>{{ title }}</h1></div>
 {% if error %}<div id="error" class="error">{{ error }}</div>{% endif %}
-<form action="" method="POST" id="{{ fname }}" name="{{ fname }}">
+<form action="{% url modoboa.extensions.sievefilters.views.new_filters_set %}" 
+      method="POST" id="{{ fname }}" name="{{ fname }}">
   {% include "common/genericform.html" %}
   <div id="submit_container">
     <input type="submit" name="submit" value='{{ submit_label }}'/>
diff --git a/extensions/sievefilters/views.py b/extensions/sievefilters/views.py
index 59774e488..70c2dba2a 100644
--- a/extensions/sievefilters/views.py
+++ b/extensions/sievefilters/views.py
@@ -28,9 +28,9 @@ def index(request, tplname="sievefilters/index.html"):
         return _render_error(request, user_context={"error" : e})
     if active_script is None:
         active_script = ""
-        default_script = scripts[0] if len(scripts) else ""
+        default_script = "%s/" % scripts[0] if len(scripts) else ""
     else:
-        default_script = active_script
+        default_script = "%s/" % active_script
     return _render(request, tplname, {
             "active_script" : active_script,
             "default_script" : default_script,
diff --git a/extensions/webmail/templates/webmail/folder.html b/extensions/webmail/templates/webmail/folder.html
index 1abc6a5b2..62af3b982 100644
--- a/extensions/webmail/templates/webmail/folder.html
+++ b/extensions/webmail/templates/webmail/folder.html
@@ -6,6 +6,8 @@
 <script src="{{ MEDIA_URL }}webmail/js/webmail.js" type="text/javascript"></script>
 <script type="text/javascript">
   window.addEvent("domready", function() {
+    var form = new Form();
+
     init_folders_browsing();
 
     $$("a[name=loadfolder]").addEvent("click", function(evt) {
@@ -16,7 +18,7 @@
       this.getParent().addClass("selected");
     });
 
-    register_extra_data_callback("{{ fname }}", function() {
+    form.register_extra_data_callback("{{ fname }}", function() {
       var result = "";
       $$("li[class*=selected]").each(function(item) {
         var atag = item.getFirst("a");
@@ -30,7 +32,8 @@
 {% block content %}
 <div class="title"><h1>{{ title }}</h1></div>
 <div id="error" class="error">{{ error }}</div>
-<form action="" method="POST" id="{{ fname }}" name="{{ fname }}">
+<form action="{% url modoboa.extensions.webmail.views.newfolder %}" 
+      method="POST" id="{{ fname }}" name="{{ fname }}">
   <input type="hidden" name="oldname" value="{{ oldname }}" />
   {% include "common/genericform.html" %}
   <div class="row">
diff --git a/static/js/form.js b/static/js/form.js
index 1aa95d98d..de570ef3a 100644
--- a/static/js/form.js
+++ b/static/js/form.js
@@ -41,7 +41,7 @@ var Form = new Class({
     },
 
     register_callback: function(category, name, callback) {
-        if (this.callbacks[category][name] == undefined) {
+        if (this.callbacks[category] == undefined) {
             return false;
         }
         this.callbacks[category][name] = callback;
@@ -82,8 +82,8 @@ var Form = new Class({
                     if (response.norefresh != undefined && response.norefresh == true) {
                         $$("div[class=error]").set("html", response.respmsg);
                     } else {
-                        var target = (this.options.target)
-                            ? $(this.options.target) : $(document.body);
+                        var target = (this.options.resptarget)
+                            ? $(this.options.resptarget) : $(document.body);
 
                         target.set("html", response.content);
                         this.init_help_messages();
@@ -124,130 +124,3 @@ var Form = new Class({
         }).send();
     }
 });
-
-
-var error_callbacks = {
-    permform: function() {
-	if ($defined($("id_domain"))) {
-	    $("id_domain").options[0].setProperty("selected", "selected");
-	    domadminform_init();
-	}
-    }
-};
-
-var success_callbacks = {
-
-};
-
-var extra_data_callbacks = {
-
-};
-
-function register_callback(hash, name, callback) {
-    if ($defined(hash[name])) {
-        return false;
-    }
-    hash[name] = callback;
-    return true;
-}
-
-function register_error_callback(name, callback) {
-    return register_callback(error_callbacks, name, callback);
-}
-
-function register_success_callback(name, callback) {
-    return register_callback(success_callbacks, name, callback);
-}
-
-function register_extra_data_callback(name, callback) {
-    return register_callback(extra_data_callbacks, name, callback);
-}
-
-function ajax_submit(event) {
-    var form = event.target;
-    var myid = form.get("id");
-    var data = form.toQueryString();
-
-    event.stop();
-    if ($defined(extra_data_callbacks[myid])) {
-        if (data != "") {
-            data += "&";
-        }
-        data += extra_data_callbacks[myid]();
-    }
-
-    new Request.JSON({
-        url: form.get("action"),
-        method: form.get("method"),
-        data: data,
-        onSuccess: function(response) {
-            if (response.status == "ko") {
-                if (response.norefresh != undefined && response.norefresh == true) {
-                    $$("div[class=error]").set("html", response.respmsg);
-                } else {
-                    var target = (resptarget != undefined)
-                        ? $(resptarget) : $(document.body);
-
-                    target.set("html", response.content);
-	            /*$(document.body).addEvent("submit", ajax_submit);*/
-	            if ($defined(error_callbacks[myid])) {
-	                error_callbacks[myid]();
-	            }
-                }
-                return;
-            }
-            if ($defined(response.respmsg)) {
-                if ($defined(parent.current_anchor)) {
-                    parent.current_anchor.loading_message = response.respmsg;
-                    parent.current_anchor.loading_color = "green";
-                } else {
-                    parent.infobox.info(response.respmsg);
-                    parent.infobox.hide(1);
-                }
-            }
-            if ($defined(response.ajaxnav)) {
-                if ($defined(response.url)) {
-                    parent.current_anchor.baseurl(response.url, 1);
-                }
-                parent.current_anchor.update(1);
-            } else if ($defined(response.url)) {
-                parent.location.href = response.url;
-            }
-            if ($defined(success_callbacks[myid])) {
-	        success_callbacks[myid](response);
-	    }
-            parent.SqueezeBox.close();
-        },
-        onFailure: function(xhr) {
-            parent.document.getElement('iframe').setStyles({width: 800, height: 600});
-            $(document.body).set("html", xhr.responseText);
-        }
-    }).send();
-}
-
-function initform() {
-    $(document.body)
-        .removeEvents("submit")
-        .addEvent("submit", ajax_submit);
-
-    $$("input[type!=submit]", "select").addEvents({
-        focus: function(evt) {
-	    var helpdiv = $(evt.target.name + "_helptext");
-	    if (helpdiv) {
-		var coords = evt.target.getCoordinates();
-		helpdiv.setPosition({x: 10, y: coords['top'] + coords['height'] + 5});
-		helpdiv.setStyle("display", "block");
-	    }
-	},
-	blur: function(evt) {
-	    var helpdiv = $(evt.target.name + "_helptext");
-	    if (helpdiv) {
-		helpdiv.setStyle("display", "none");
-	    }
-	}
-    });
-}
-
-/*window.addEvent("domready", function() {
-    initform();
-});*/
diff --git a/templates/admin/add_domain_admin.html b/templates/admin/add_domain_admin.html
index 1c4dd537c..482bcf734 100644
--- a/templates/admin/add_domain_admin.html
+++ b/templates/admin/add_domain_admin.html
@@ -8,7 +8,7 @@
 <script type="text/javascript" src="{{ MEDIA_URL }}js/Autocompleter.Request.js"></script>
 <script type="text/javascript">
 window.addEvent("domready", function() {
-    var form = new Form({target: "formcontainer"});
+    var form = new Form({resptarget: "formcontainer"});
 
 $("createfrom").addEvent("change", function(evt) {
     var url = "";
diff --git a/templates/userprefs/setforward.html b/templates/userprefs/setforward.html
index 67659ca3c..8f9fab986 100644
--- a/templates/userprefs/setforward.html
+++ b/templates/userprefs/setforward.html
@@ -1,6 +1,11 @@
 {% extends "layout_simple.html" %}
 {% block html_head %}
 <script src="{{ MEDIA_URL }}js/form.js" type="text/javascript"></script>
+<script type="text/javascript">
+window.addEvent("domready", function() {
+    var form = new Form();
+});
+</script>
 {% endblock %}
 {% block content %}
 {% load i18n %}