diff --git a/modoboa/sievefilters/api/v2/serializers.py b/modoboa/sievefilters/api/v2/serializers.py
index e7c6b32f2..a8ab5a0a1 100644
--- a/modoboa/sievefilters/api/v2/serializers.py
+++ b/modoboa/sievefilters/api/v2/serializers.py
@@ -5,12 +5,9 @@ from typing import List, Tuple
 from sievelib import commands
 from sievelib.factory import Filter
 
-from django.utils.translation import gettext as _
-
 from rest_framework import serializers
 
 from modoboa.sievefilters import constants, lib
-from modoboa.sievefilters.forms import supported_auth_mechs
 from modoboa.sievefilters.api.v2 import vloaders
 
 
@@ -22,19 +19,12 @@ class SievefiltersSettingsSerializer(serializers.Serializer):
     server = serializers.CharField(default="127.0.0.1")
     port = serializers.IntegerField(default=4190)
     starttls = serializers.BooleanField(default=False)
-    authentication_mech = serializers.ChoiceField(
-        default="auto", choices=[("auto", _("auto"))]
-    )
 
     # Imap Settings
     imap_server = serializers.CharField(default="127.0.0.1")
     imap_secured = serializers.BooleanField(default=False)
     imap_port = serializers.IntegerField(default=143)
 
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        self.fields["authentication_mech"].choices = supported_auth_mechs()
-
 
 class FilterSetSerializer(serializers.Serializer):
     name = serializers.CharField()
diff --git a/modoboa/sievefilters/api/v2/tests.py b/modoboa/sievefilters/api/v2/tests.py
index b72e4c798..18b7a781c 100644
--- a/modoboa/sievefilters/api/v2/tests.py
+++ b/modoboa/sievefilters/api/v2/tests.py
@@ -1,19 +1,22 @@
 """API v2 tests."""
 
 from unittest import mock
+from datetime import timezone, timedelta
 
 from django.urls import reverse
 
-from rest_framework.authtoken.models import Token
+from oauth2_provider.models import get_access_token_model, get_application_model
 
 from modoboa.admin import factories as admin_factories
 from modoboa.core import models as core_models
 from modoboa.lib.tests import ModoAPITestCase
 from modoboa.sievefilters import mocks
 
+Application = get_application_model()
+AccessToken = get_access_token_model()
+
 
 class FilterSetViewSetTestCase(ModoAPITestCase):
-
     @classmethod
     def setUpTestData(cls):
         """Create some users."""
@@ -21,6 +24,22 @@ class FilterSetViewSetTestCase(ModoAPITestCase):
         admin_factories.populate_database()
         cls.user = core_models.User.objects.get(username="user@test.com")
 
+        cls.application = Application.objects.create(
+            name="Test Application",
+            redirect_uris="http://localhost",
+            user=cls.user,
+            client_type=Application.CLIENT_PUBLIC,
+            authorization_grant_type=Application.GRANT_AUTHORIZATION_CODE,
+        )
+
+        cls.access_token = AccessToken.objects.create(
+            user=cls.test_user,
+            scope="read write",
+            expires=timezone.now() + timedelta(seconds=300),
+            token="secret-access-token-key",
+            application=cls.application,
+        )
+
     def setUp(self):
         """Connect with a simpler user."""
         super().setUp()
@@ -35,11 +54,7 @@ class FilterSetViewSetTestCase(ModoAPITestCase):
         self.addCleanup(patcher.stop)
 
     def authenticate(self, username: str = "user@test.com"):
-        # FIXME: replace ASAP with an oauth2 token
-        token = Token.objects.create(
-            user=core_models.User.objects.get(username=username)
-        )
-        self.client.credentials(HTTP_AUTHORIZATION="Token " + token.key)
+        self.client.credentials(Authorization="Bearer " + self.access_token.token)
 
     def test_list(self):
         self.authenticate()
diff --git a/modoboa/sievefilters/api/v2/viewsets.py b/modoboa/sievefilters/api/v2/viewsets.py
index 51b822135..2d701d7da 100644
--- a/modoboa/sievefilters/api/v2/viewsets.py
+++ b/modoboa/sievefilters/api/v2/viewsets.py
@@ -29,7 +29,6 @@ FILTER_SET_ID = OpenApiParameter(
 
 
 class FilterSetViewSet(viewsets.ViewSet):
-
     permission_classes = (HasMailbox,)
     serializer_class = serializers.FilterSetSerializer
 
diff --git a/modoboa/sievefilters/app_settings.py b/modoboa/sievefilters/app_settings.py
index 339252e44..182b99a4c 100644
--- a/modoboa/sievefilters/app_settings.py
+++ b/modoboa/sievefilters/app_settings.py
@@ -35,13 +35,6 @@ SIEVEFILTERS_PARAMETERS_STRUCT = collections.OrderedDict(
                                 "help_text": _("Use the STARTTLS extension"),
                             },
                         ),
-                        (
-                            "authentication_mech",
-                            {
-                                "label": _("Authentication mechanism"),
-                                "help_text": _("Prefered authentication mechanism"),
-                            },
-                        ),
                     ]
                 ),
             },
diff --git a/modoboa/sievefilters/forms.py b/modoboa/sievefilters/forms.py
index feb8a4dfa..1fb2af009 100644
--- a/modoboa/sievefilters/forms.py
+++ b/modoboa/sievefilters/forms.py
@@ -1,7 +1,5 @@
 """Custom forms."""
 
-from sievelib.managesieve import SUPPORTED_AUTH_MECHS
-
 from django import forms
 from django.utils.translation import gettext_lazy
 
@@ -9,13 +7,6 @@ from modoboa.lib import form_utils
 from modoboa.parameters import forms as param_forms
 
 
-def supported_auth_mechs():
-    values = [("AUTO", "auto")]
-    for m in SUPPORTED_AUTH_MECHS:
-        values += [(m, m.lower())]
-    return values
-
-
 class ParametersForm(param_forms.AdminParametersForm):
     app = "sievefilters"
 
@@ -41,14 +32,6 @@ class ParametersForm(param_forms.AdminParametersForm):
         help_text=gettext_lazy("Use the STARTTLS extension"),
     )
 
-    authentication_mech = forms.ChoiceField(
-        label=gettext_lazy("Authentication mechanism"),
-        choices=supported_auth_mechs(),
-        initial="auto",
-        help_text=gettext_lazy("Prefered authentication mechanism"),
-        widget=forms.Select(attrs={"class": "form-control"}),
-    )
-
     sep2 = form_utils.SeparatorField(label=gettext_lazy("IMAP settings"))
 
     imap_server = forms.CharField(
diff --git a/modoboa/sievefilters/lib.py b/modoboa/sievefilters/lib.py
index 207f08cd0..e0617a635 100644
--- a/modoboa/sievefilters/lib.py
+++ b/modoboa/sievefilters/lib.py
@@ -1,6 +1,5 @@
 """Internal tools."""
 
-import ssl
 from typing import Optional, Tuple, Union
 
 from sievelib.factory import FiltersSet
@@ -25,10 +24,10 @@ class SieveClient:
 
     msc: managesieve.Client
 
-    def __init__(self, user: Optional[str] = None, password: Optional[str] = None):
-        if user and password:
+    def __init__(self, user: Optional[str] = None, oauth_token: Optional[str] = None):
+        if user and oauth_token:
             try:
-                ret, msg = self.login(user, password)
+                ret, msg = self.login(user, oauth_token)
             except (managesieve.Error, ConnectionError) as e:
                 raise SieveClientError(str(e))
             if not ret:
@@ -37,12 +36,9 @@ class SieveClient:
     def login(self, user: str, password: str) -> Tuple[bool, Union[str, None]]:
         conf = dict(param_tools.get_global_parameters("sievefilters"))
         self.msc = managesieve.Client(conf["server"], conf["port"], debug=True)
-        authmech = conf["authentication_mech"]
-        if authmech == "AUTO":
-            authmech = None
         try:
             ret = self.msc.connect(
-                user, password, starttls=conf["starttls"], authmech=authmech
+                user, password, starttls=conf["starttls"], authmech="OAUTHBEARER"
             )
         except managesieve.Error as err:
             print(err)
diff --git a/modoboa/sievefilters/mocks.py b/modoboa/sievefilters/mocks.py
index f80c04742..e1e2b3632 100644
--- a/modoboa/sievefilters/mocks.py
+++ b/modoboa/sievefilters/mocks.py
@@ -2,7 +2,6 @@
 
 """Mock objects."""
 
-
 SAMPLE_SIEVE_SCRIPT = """require ["fileinto", "copy"];
 
 # Filter: test1
@@ -63,7 +62,7 @@ class ManagesieveClientMock:
         return """
 "IMPLEMENTATION" "Example1 ManageSieved v001"
 "VERSION" "1.0"
-"SASL" "PLAIN SCRAM-SHA-1 GSSAPI"
+"SASL" "PLAIN SCRAM-SHA-1 GSSAPI OAUTHBEARER"
 "SIEVE" "fileinto vacation"
 "STARTTLS"
 """