diff --git a/docker/dovecot_config/auth-custom.conf b/docker/dovecot_config/auth-custom.conf
index 923b0f36c..d7a430050 100644
--- a/docker/dovecot_config/auth-custom.conf
+++ b/docker/dovecot_config/auth-custom.conf
@@ -5,6 +5,10 @@ auth_debug = yes
 auth_verbose = yes
 auth_debug_passwords = yes
 
+# Disabling SSL (dev)
+ssl=no
+disable_plaintext_auth=no
+
 passdb {
   driver = oauth2
   mechanisms = xoauth2 oauthbearer
diff --git a/frontend/src/api/repository.js b/frontend/src/api/repository.js
index 9c23ab68a..15725b251 100644
--- a/frontend/src/api/repository.js
+++ b/frontend/src/api/repository.js
@@ -36,8 +36,10 @@ _axios.interceptors.response.use(
       return Promise.reject(error)
     }
     if (error.response.status !== 401 || router.currentRoute.name === 'Login') {
-      const busStore = useBusStore()
-      busStore.displayNotification({ msg: error.response.data, type: 'error' })
+      if (error.response.status !== 518) {
+        const busStore = useBusStore()
+        busStore.displayNotification({ msg: error.response.data, type: 'error' })
+      }
       return Promise.reject(error)
     }
     const refreshToken = Cookies.get('refreshToken')
diff --git a/frontend/src/views/account/FiltersView.vue b/frontend/src/views/account/FiltersView.vue
index b4621b002..5762f0485 100644
--- a/frontend/src/views/account/FiltersView.vue
+++ b/frontend/src/views/account/FiltersView.vue
@@ -200,6 +200,9 @@ function getFilterSetName(filterSet) {
   if (filterSet.active) {
     result += ' (' + $gettext('active') + ')'
   }
+  else {
+    result += ' (' + $gettext('inactive') + ')'
+  }
   return result
 }
 
@@ -216,7 +219,12 @@ function closeFilterForm() {
 
 function fetchFilterSets() {
   accountApi.getFilterSets().then(resp => {
-    filterSets.value = resp.data
+    if (resp.data.length > 0 && resp.data[0].active && resp.data[0].name === null) {
+      // No filter is active
+      filterSets.value = resp.data.slice(1)
+    } else {
+      filterSets.value = resp.data
+    }
     if (!currentFilterSet.value && route.params.filterset) {
       for (const filterSet of filterSets.value) {
         if (filterSet.name === route.params.filterset) {
@@ -233,6 +241,12 @@ function fetchFilters(filterSetName) {
   accountApi.getFilters(filterSetName).then(resp => {
     filters.value = resp.data
     loadingFilters.value = false
+  }).catch(error => {
+    if (error.response.status === 518) { // Server is a teapot (sieve file contains custom code or is broken)
+      // Let the user see with rawmode
+      rawMode.value = true
+      busStore.displayNotification({ msg: $gettext('Failed to display template. Using raw mode'), type: 'warning' })
+    }
   })
 }
 
diff --git a/modoboa/core/checks.py b/modoboa/core/checks.py
index a1e6b7348..ca61a40af 100644
--- a/modoboa/core/checks.py
+++ b/modoboa/core/checks.py
@@ -1,4 +1,4 @@
-from django.db.utils import ProgrammingError
+from django.db.utils import ProgrammingError, OperationalError
 from django.core.checks import register, Info, Warning
 from django.conf import settings
 from django.utils.translation import gettext as _
@@ -53,7 +53,7 @@ def check_password_hasher(app_configs, **kwargs):
     msgs = []
     try:
         hasher = check_for_deprecated_password_schemes()
-    except ProgrammingError:
+    except (ProgrammingError, OperationalError):
         # This is probably a fresh install...
         return []
     if hasher:
diff --git a/modoboa/sievefilters/api/v2/tests.py b/modoboa/sievefilters/api/v2/tests.py
index 3c95743b4..bd33fc83a 100644
--- a/modoboa/sievefilters/api/v2/tests.py
+++ b/modoboa/sievefilters/api/v2/tests.py
@@ -137,6 +137,9 @@ class FilterSetViewSetTestCase(ModoAPITestCase):
         resp = self.client.get(url)
         self.assertEqual(resp.status_code, 200)
         self.assertEqual(len(resp.json()), 5)
+        url = reverse("v2:filterset-get-filters", args=["complex_script"])
+        resp = self.client.get(url)
+        self.assertEqual(resp.status_code, 518)
 
     def test_add_filter(self):
         self.authenticate()
diff --git a/modoboa/sievefilters/api/v2/viewsets.py b/modoboa/sievefilters/api/v2/viewsets.py
index 2d701d7da..52d7fca9f 100644
--- a/modoboa/sievefilters/api/v2/viewsets.py
+++ b/modoboa/sievefilters/api/v2/viewsets.py
@@ -15,7 +15,7 @@ from rest_framework.decorators import action
 
 from modoboa.lib.viewsets import HasMailbox
 from modoboa.sievefilters import constants
-from modoboa.sievefilters.lib import SieveClient, SieveClientError
+from modoboa.sievefilters.lib import SieveClient, SieveClientError, SieveActionTemplateNotFound
 from modoboa.sievefilters.rfc6266 import build_header
 from modoboa.sievefilters.api.v2 import serializers
 
@@ -154,7 +154,10 @@ class FilterSetViewSet(viewsets.ViewSet):
             fset = sclient.getscript(pk, format="fset")
         except SieveClientError:
             return response.Response(status=404)
-        serializer = serializers.FilterSerializer.from_filters(fset.filters)
+        try:
+            serializer = serializers.FilterSerializer.from_filters(fset.filters)
+        except SieveActionTemplateNotFound:
+            return HttpResponse(status=518)
         return response.Response(serializer.data)
 
     @extend_schema(
diff --git a/modoboa/sievefilters/lib.py b/modoboa/sievefilters/lib.py
index 481b17b8f..066035f68 100644
--- a/modoboa/sievefilters/lib.py
+++ b/modoboa/sievefilters/lib.py
@@ -19,6 +19,10 @@ class SieveClientError(ModoboaException):
     http_code = 400
 
 
+class SieveActionTemplateNotFound(Exception):
+    pass
+
+
 class SieveClient:
     """Sieve client."""
 
@@ -93,4 +97,4 @@ def find_action_template(action: str):
     for tpl in constants.ACTION_TEMPLATES:
         if tpl["name"] == action:
             return tpl
-    raise RuntimeError(f"action {action} not defined")
+    raise SieveActionTemplateNotFound(f"action {action} not defined")
diff --git a/modoboa/sievefilters/mocks.py b/modoboa/sievefilters/mocks.py
index e1e2b3632..baad7283f 100644
--- a/modoboa/sievefilters/mocks.py
+++ b/modoboa/sievefilters/mocks.py
@@ -39,6 +39,15 @@ if anyof (header :contains "Subject" "toto", not header :contains "To" "peé") {
 }
 """
 
+SAMPLE_COMPLEX_SCRIPT = """require ["imap4flags"];
+
+# Filter: Test42
+if anyof (header :contains "From" "TOBESEEN") {
+    setflag "\\seen";
+}
+
+"""
+
 
 class ManagesieveClientMock:
     """Fake managesieve client."""
@@ -50,6 +59,7 @@ class ManagesieveClientMock:
             "main_script": SAMPLE_SIEVE_SCRIPT,
             "second_script": SAMPLE_SIEVE_SCRIPT,
             "third_script": SAMPLE_SIEVE_SCRIPT2,
+            "complex_script": SAMPLE_COMPLEX_SCRIPT,
         }
 
     def connect(self, username, password, **kwargs):