diff --git a/frontend/src/api/transports.js b/frontend/src/api/transports.js
new file mode 100644
index 000000000..0fad80284
--- /dev/null
+++ b/frontend/src/api/transports.js
@@ -0,0 +1,9 @@
+import repository from './repository'
+
+const resource = 'transports'
+
+export default {
+  getAll () {
+    return repository.get(`/${resource}/`)
+  }
+}
diff --git a/frontend/src/components/domains/DomainCreationForm.vue b/frontend/src/components/domains/DomainCreationForm.vue
index 1084f9a0a..f64c0f007 100644
--- a/frontend/src/components/domains/DomainCreationForm.vue
+++ b/frontend/src/components/domains/DomainCreationForm.vue
@@ -20,6 +20,9 @@
   <template v-slot:form.options="{ step }">
     <domain-options-form :ref="`form_${step}`" :domain="domain" @createAdmin="updateCreateAdmin" />
   </template>
+  <template v-slot:form.transport="{ step }">
+    <domain-transport-form :ref="`form_${step}`" :domain="domain" />
+  </template>
   <template v-slot:item.with_random_password="{ item }">
     <template v-if="item.value">
       <v-col cols="12" class="highligth white--text">
@@ -52,6 +55,7 @@ import DomainDNSForm from './DomainDNSForm'
 import DomainGeneralForm from './DomainGeneralForm'
 import DomainLimitationsForm from './DomainLimitationsForm'
 import DomainOptionsForm from './DomainOptionsForm'
+import DomainTransportForm from './DomainTransportForm'
 
 export default {
   props: ['value'],
@@ -60,7 +64,8 @@ export default {
     'domain-dns-form': DomainDNSForm,
     DomainGeneralForm,
     DomainLimitationsForm,
-    DomainOptionsForm
+    DomainOptionsForm,
+    DomainTransportForm
   },
   computed: {
     summarySections () {
@@ -87,12 +92,6 @@ export default {
             { key: this.$gettext('Default mailbox quota'), value: this.domain.default_mailbox_quota },
             { key: this.$gettext('Message sending limit'), value: this.domain.message_sending_limit }
           ]
-        },
-        {
-          title: this.$gettext('Options'),
-          items: [
-            { key: this.$gettext('Create a domain administrator'), value: this.createAdmin, type: 'yesno' }
-          ]
         }
       ]
       if (this.domain.enable_dkim) {
@@ -100,25 +99,53 @@ export default {
         result[1].items.push({ key: this.$gettext('DKIM key length'), value: this.domain.dkim_key_length })
       }
       if (this.createAdmin) {
-        result[3].items.push({ key: this.$gettext('Administrator name'), value: this.domain.domain_admin.username })
-        result[3].items.push({
-          name: 'with_random_password',
-          key: this.$gettext('Random password'),
-          value: this.domain.domain_admin.with_random_password,
-          type: 'yesno'
-        })
-        result[3].items.push({
-          key: this.$gettext('With mailbox'),
-          value: this.domain.domain_admin.with_mailbox,
-          type: 'yesno'
-        })
-        result[3].items.push({
-          key: this.$gettext('Create aliases'),
-          value: this.domain.domain_admin.with_aliases,
-          type: 'yesno'
+        result.push({
+          title: this.$gettext('Options'),
+          items: [
+            { key: this.$gettext('Create a domain administrator'), value: this.createAdmin, type: 'yesno' },
+            { key: this.$gettext('Administrator name'), value: this.domain.domain_admin.username },
+            {
+              name: 'with_random_password',
+              key: this.$gettext('Random password'),
+              value: this.domain.domain_admin.with_random_password,
+              type: 'yesno'
+            },
+            {
+              key: this.$gettext('With mailbox'),
+              value: this.domain.domain_admin.with_mailbox,
+              type: 'yesno'
+            },
+            {
+              key: this.$gettext('Create aliases'),
+              value: this.domain.domain_admin.with_aliases,
+              type: 'yesno'
+            }
+          ]
         })
       }
+      if (this.domain.type === 'relaydomain') {
+        const relayEntry = {
+          title: this.$gettext('Transport'),
+          items: [
+            { key: this.$gettext('Service'), value: this.domain.transport.service }
+          ]
+        }
+        if (this.$refs.form_4.service) {
+          const service = this.$refs.form_4.service
+          for (const setting of service.settings) {
+            const item = { key: setting.label, value: this.domain.transport.settings[`${service.name}_${setting.name}`] }
+            if (setting.type === 'boolean') {
+              item.type = 'yesno'
+            }
+            relayEntry.items.push(item)
+          }
+        }
+        result.push(relayEntry)
+      }
       return result
+    },
+    steps () {
+      return this.domain.type === 'domain' ? this.domainSteps : this.relaySteps
     }
   },
   data () {
@@ -128,11 +155,17 @@ export default {
         domain_admin: {}
       },
       formErrors: {},
-      steps: [
+      domainSteps: [
         { name: 'general', title: this.$gettext('General') },
         { name: 'dns', title: this.$gettext('DNS') },
         { name: 'limitations', title: this.$gettext('Limitations') },
         { name: 'options', title: this.$gettext('Options') }
+      ],
+      relaySteps: [
+        { name: 'general', title: this.$gettext('General') },
+        { name: 'dns', title: this.$gettext('DNS') },
+        { name: 'limitations', title: this.$gettext('Limitations') },
+        { name: 'transport', title: this.$gettext('Transport') }
       ]
     }
   },
@@ -160,7 +193,8 @@ export default {
           with_random_password: false,
           with_mailbox: false,
           with_aliases: false
-        }
+        },
+        transport: {}
       }
     },
     close () {
@@ -181,6 +215,9 @@ export default {
       if (!this.createAdmin) {
         delete data.domain_admin
       }
+      if (data.type === 'relaydomain') {
+        this.$refs.form_4.checkSettingTypes(data)
+      }
       this.$store.dispatch('domains/createDomain', data).then(resp => {
         this.$router.push({ name: 'DomainDetail', params: { id: resp.data.pk } })
         bus.$emit('notification', { msg: this.$gettext('Domain created') })
diff --git a/frontend/src/components/domains/DomainForm.vue b/frontend/src/components/domains/DomainForm.vue
index 91d59b351..35eb84811 100644
--- a/frontend/src/components/domains/DomainForm.vue
+++ b/frontend/src/components/domains/DomainForm.vue
@@ -104,6 +104,35 @@
         <domain-limitations-form :domain="editedDomain" />
       </v-expansion-panel-content>
     </v-expansion-panel>
+    <v-expansion-panel v-if="editedDomain.type === 'relaydomain'">
+      <v-expansion-panel-header v-slot="{ open }">
+        <v-row no-gutters>
+          <v-col cols="4">
+            <translate>Transport</translate>
+          </v-col>
+          <v-col
+            cols="8"
+            class="text--secondary"
+            >
+            <v-fade-transition leave-absolute>
+              <span v-if="open"></span>
+              <v-row
+                v-else
+                no-gutters
+                style="width: 100%"
+                >
+                <v-col cols="6">
+                  <translate class="mr-2">Service: </translate> {{ editedDomain.transport.service }}
+                </v-col>
+              </v-row>
+            </v-fade-transition>
+          </v-col>
+        </v-row>
+      </v-expansion-panel-header>
+      <v-expansion-panel-content>
+        <domain-transport-form ref="transportForm" :domain="editedDomain" />
+      </v-expansion-panel-content>
+    </v-expansion-panel>
   </v-expansion-panels>
   <div class="mt-4 d-flex justify-end">
     <v-btn color="grey lighten-1" @click="$router.go(-1)">
@@ -121,12 +150,14 @@ import { bus } from '@/main'
 import DomainDNSForm from './DomainDNSForm'
 import DomainGeneralForm from './DomainGeneralForm'
 import DomainLimitationsForm from './DomainLimitationsForm'
+import DomainTransportForm from './DomainTransportForm'
 
 export default {
   components: {
     'domain-dns-form': DomainDNSForm,
     DomainGeneralForm,
-    DomainLimitationsForm
+    DomainLimitationsForm,
+    DomainTransportForm
   },
   props: ['domain'],
   data () {
@@ -143,6 +174,9 @@ export default {
           return
         }
       }
+      if (this.editedDomain.type === 'relaydomain') {
+        this.$refs.transportForm.checkSettingTypes(this.editedDomain)
+      }
       this.$store.dispatch('domains/updateDomain', this.editedDomain).then(resp => {
         bus.$emit('notification', { msg: this.$gettext('Domain updated') })
       })
@@ -156,6 +190,11 @@ export default {
         }
       },
       immediate: true
+    },
+    'editedDomain.type' (val) {
+      if (val === 'relaydomain' && this.editedDomain.transport === null) {
+        this.$set(this.editedDomain, 'transport', {})
+      }
     }
   }
 }
diff --git a/frontend/src/components/domains/DomainList.vue b/frontend/src/components/domains/DomainList.vue
index 8890ecaf4..be5958cbd 100644
--- a/frontend/src/components/domains/DomainList.vue
+++ b/frontend/src/components/domains/DomainList.vue
@@ -42,6 +42,14 @@
           <router-link :to="{ name: 'DomainDetail', params: { id: item.pk } }">
             {{ item.name }}
           </router-link>
+          <v-chip
+            v-if="item.type === 'relaydomain'"
+            small
+            color="primary"
+            class="ml-2"
+            >
+            <translate>Relay</translate>
+          </v-chip>
           <translate v-if="!item.enabled" class="ml-2 grey--text">(disabled)</translate>
         </td>
         <td>
diff --git a/frontend/src/components/domains/DomainTransportForm.vue b/frontend/src/components/domains/DomainTransportForm.vue
new file mode 100644
index 000000000..7557996ac
--- /dev/null
+++ b/frontend/src/components/domains/DomainTransportForm.vue
@@ -0,0 +1,104 @@
+<template>
+<div>
+  <validation-observer ref="observer">
+    <label class="m-label"><translate>Service</translate></label>
+    <validation-provider
+      v-slot="{ errors }"
+      rules="required"
+      >
+      <v-autocomplete
+        v-model="service"
+        :items="backends"
+        item-text="name"
+        return-object
+        outlined
+        @change="resetForm"
+        :error-messages="errors"
+        />
+    </validation-provider>
+    <template v-if="service">
+      <template v-for="setting in service.settings">
+        <div :key="setting.name">
+          <validation-provider
+            v-slot="{ errors }"
+            :rules="setting.required ? 'required' : ''"
+            >
+            <template
+              v-if="setting.type === 'str' || setting.type === 'int'"
+              >
+              <label class="m-label">{{ setting.label }}</label>
+              <v-text-field
+                v-model="domain.transport.settings[`${service.name}_${setting.name}`]"
+                outlined
+                :error-messages="errors"
+                :type="setting.type === 'int' ? 'number' : 'text'"
+                />
+            </template>
+            <v-checkbox
+              v-else-if="setting.type === 'boolean'"
+              v-model="domain.transport.settings[`${service.name}_${setting.name}`]"
+              :label="setting.label"
+              :error-messages="errors"
+              />
+          </validation-provider>
+        </div>
+      </template>
+    </template>
+  </validation-observer>
+</div>
+</template>
+
+<script>
+import transports from '@/api/transports'
+
+export default {
+  props: {
+    domain: Object
+  },
+  data () {
+    return {
+      backends: [],
+      service: null
+    }
+  },
+  methods: {
+    resetForm (value) {
+      this.$set(this.domain, 'transport', { service: value.name, settings: {} })
+      for (const setting of value.settings) {
+        if (setting.default) {
+          let defaultValue = setting.default
+          if (setting.type === 'int') {
+            defaultValue = parseInt(defaultValue)
+          } else if (setting.type === 'boolean') {
+            if (defaultValue === 'False') {
+              defaultValue = false
+            } else {
+              defaultValue = true
+            }
+          }
+          this.$set(this.domain.transport.settings, `${value.name}_${setting.name}`, defaultValue)
+        }
+      }
+    },
+    checkSettingTypes (data) {
+      for (const setting of this.service.settings) {
+        if (setting.type === 'int') {
+          const fullName = `${this.service.name}_${setting.name}`
+          data.transport.settings[fullName] = parseInt(data.transport.settings[fullName])
+        }
+      }
+    }
+  },
+  mounted () {
+    transports.getAll().then(resp => {
+      this.backends = resp.data
+      if (this.domain) {
+        this.service = this.backends.find(backend => backend.name === this.domain.transport.service)
+      }
+    })
+  },
+  watch: {
+
+  }
+}
+</script>
diff --git a/frontend/src/components/domains/TransportForm.vue b/frontend/src/components/domains/TransportForm.vue
new file mode 100644
index 000000000..e69de29bb
diff --git a/modoboa/admin/api/v2/serializers.py b/modoboa/admin/api/v2/serializers.py
index 9c2d77829..3e15e5151 100644
--- a/modoboa/admin/api/v2/serializers.py
+++ b/modoboa/admin/api/v2/serializers.py
@@ -18,6 +18,8 @@ from modoboa.lib import fields as lib_fields
 from modoboa.lib import validators, web_utils
 from modoboa.lib.sysutils import exec_cmd
 from modoboa.parameters import tools as param_tools
+from modoboa.transport import models as transport_models
+from modoboa.transport.api.v2 import serializers as transport_serializers
 
 from ... import constants, models
 
@@ -34,17 +36,33 @@ class CreateDomainAdminSerializer(serializers.Serializer):
 class DomainSerializer(v1_serializers.DomainSerializer):
     """Domain serializer for v2 API."""
 
-    domain_admin = CreateDomainAdminSerializer(required=False)
+    domain_admin = CreateDomainAdminSerializer(required=False, write_only=True)
+    transport = transport_serializers.TransportSerializer(required=False)
 
     class Meta(v1_serializers.DomainSerializer.Meta):
         fields = v1_serializers.DomainSerializer.Meta.fields + (
-            "domain_admin",
+            "domain_admin", "transport"
         )
 
+    def validate(self, data):
+        result = super().validate(data)
+        dtype = data.get("type", "domain")
+        if dtype == "relaydomain" and not data.get("transport"):
+            raise serializers.ValidationError({"transport": _("This field is required")})
+        return result
+
     def create(self, validated_data):
         """Create administrator and other stuff if needed."""
         domain_admin = validated_data.pop("domain_admin", None)
+        transport_def = validated_data.pop("transport", None)
         domain = super().create(validated_data)
+        if transport_def:
+            transport = transport_models.Transport(**transport_def)
+            transport.pattern = domain.name
+            transport.save()
+            domain.transport = transport
+            domain.save()
+
         if not domain_admin:
             return domain
 
@@ -99,6 +117,27 @@ class DomainSerializer(v1_serializers.DomainSerializer):
         domain.add_admin(da)
         return domain
 
+    def update(self, instance, validated_data):
+        """Update domain and create/update transport."""
+        transport_def = validated_data.pop("transport", None)
+        super().update(instance, validated_data)
+        if transport_def and instance.type == "relaydomain":
+            transport = getattr(instance, "transport", None)
+            created = False
+            if transport:
+                for key, value in transport_def.items():
+                    setattr(instance, key, value)
+                transport._settings = transport_def["_settings"]
+            else:
+                transport = transport_models.Transport(**transport_def)
+                created = True
+            transport.pattern = instance.name
+            transport.save()
+            if created:
+                instance.transport = transport
+                instance.save()
+        return instance
+
 
 class DeleteDomainSerializer(serializers.Serializer):
     """Serializer used with delete operation."""
diff --git a/modoboa/admin/api/v2/tests.py b/modoboa/admin/api/v2/tests.py
index 09b83a756..82c87bdd7 100644
--- a/modoboa/admin/api/v2/tests.py
+++ b/modoboa/admin/api/v2/tests.py
@@ -41,6 +41,33 @@ class DomainViewSetTestCase(ModoAPITestCase):
                 address="postmaster@domain.tld").exists()
         )
 
+    def test_update(self):
+        domain = models.Domain.objects.get(name="test2.com")
+        data = {
+            "name": "test2.com",
+            "type": "relaydomain",
+            "transport": {
+                "service": "relay",
+                "settings": {
+                    "relay_target_port": 25,
+                    "relay_target_host": "localhost"
+                }
+            }
+        }
+        url = reverse("v2:domain-detail", args=[domain.pk])
+        resp = self.client.put(url, data, format="json")
+        self.assertEqual(resp.status_code, 200)
+        domain.refresh_from_db()
+        self.assertEqual(domain.transport.service, data["transport"]["service"])
+        self.assertEqual(
+            domain.transport._settings["relay_target_host"],
+            data["transport"]["settings"]["relay_target_host"]
+        )
+
+        data["transport"]["relay_verify_recipients"] = True
+        resp = self.client.put(url, data, format="json")
+        self.assertEqual(resp.status_code, 200)
+
     def test_delete(self):
         self.client.credentials(
             HTTP_AUTHORIZATION="Token " + self.da_token.key)
diff --git a/modoboa/admin/api/v2/viewsets.py b/modoboa/admin/api/v2/viewsets.py
index bacdcf5b5..7527d7d27 100644
--- a/modoboa/admin/api/v2/viewsets.py
+++ b/modoboa/admin/api/v2/viewsets.py
@@ -58,15 +58,13 @@ class DomainViewSet(lib_viewsets.RevisionModelMixin,
         return models.Domain.objects.get_for_admin(self.request.user)
 
     def get_serializer_class(self, *args, **kwargs):
-        if self.action == "create":
-            return serializers.DomainSerializer
         if self.action == "delete":
             return serializers.DeleteDomainSerializer
         if self.action == "administrators":
             return serializers.DomainAdminSerializer
         if self.action in ["add_administrator", "remove_administrator"]:
             return serializers.SimpleDomainAdminSerializer
-        return v1_serializers.DomainSerializer
+        return serializers.DomainSerializer
 
     @action(methods=["post"], detail=True)
     def delete(self, request, **kwargs):
diff --git a/modoboa/transport/api/__init__.py b/modoboa/transport/api/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/modoboa/transport/api/v2/__init__.py b/modoboa/transport/api/v2/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/modoboa/transport/api/v2/serializers.py b/modoboa/transport/api/v2/serializers.py
new file mode 100644
index 000000000..7ce8aa984
--- /dev/null
+++ b/modoboa/transport/api/v2/serializers.py
@@ -0,0 +1,42 @@
+"""Transport related serializers."""
+
+from rest_framework import serializers
+
+from ... import backends
+from ... import models
+
+
+class TransportBackendSettingSerializer(serializers.Serializer):
+    """Serializer for transport backend setting."""
+
+    name = serializers.CharField()
+    label = serializers.CharField()
+    type = serializers.CharField(default="str")
+    required = serializers.BooleanField(default=True)
+    default = serializers.CharField(default=None)
+
+
+class TransportBackendSerializer(serializers.Serializer):
+    """Serializer for transport backend."""
+
+    name = serializers.CharField()
+    settings = TransportBackendSettingSerializer(many=True)
+
+
+class TransportSerializer(serializers.ModelSerializer):
+    """Serializer for Transport model."""
+
+    settings = serializers.DictField(source="_settings")
+
+    class Meta:
+        fields = ("service", "settings")
+        model = models.Transport
+
+    def validate(self, data):
+        self.backend = backends.manager.get_backend(data["service"])
+        errors = {}
+        for field, error in self.backend.clean_fields(data["_settings"]):
+            errors[field] = error
+        if errors:
+            raise serializers.ValidationError(errors)
+        return data
diff --git a/modoboa/transport/api/v2/tests.py b/modoboa/transport/api/v2/tests.py
new file mode 100644
index 000000000..790ba2ea6
--- /dev/null
+++ b/modoboa/transport/api/v2/tests.py
@@ -0,0 +1,16 @@
+"""API v2 tests."""
+
+from django.urls import reverse
+
+from modoboa.lib.tests import ModoAPITestCase
+
+
+class TransportViewSetTestCase(ModoAPITestCase):
+
+    def test_list(self):
+        url = reverse("v2:transport-list")
+        resp = self.client.get(url)
+        self.assertEqual(resp.status_code, 200)
+        backends = resp.json()
+        self.assertEqual(len(backends), 1)
+        self.assertEqual(backends[0]["name"], "relay")
diff --git a/modoboa/transport/api/v2/urls.py b/modoboa/transport/api/v2/urls.py
new file mode 100644
index 000000000..816410035
--- /dev/null
+++ b/modoboa/transport/api/v2/urls.py
@@ -0,0 +1,12 @@
+"""App related urls."""
+
+from rest_framework import routers
+
+from . import viewsets
+
+
+router = routers.SimpleRouter()
+router.register(
+    r"transports", viewsets.TransportViewSet, basename="transport")
+
+urlpatterns = router.urls
diff --git a/modoboa/transport/api/v2/viewsets.py b/modoboa/transport/api/v2/viewsets.py
new file mode 100644
index 000000000..28d2b005f
--- /dev/null
+++ b/modoboa/transport/api/v2/viewsets.py
@@ -0,0 +1,27 @@
+"""Transport related viewsets."""
+
+from drf_spectacular.utils import extend_schema
+from rest_framework import permissions, response, viewsets
+
+from . import serializers
+from ... import backends
+
+
+class TransportViewSet(viewsets.ViewSet):
+    """Viewset for Transport."""
+
+    permissions = (permissions.IsAuthenticated, )
+
+    @extend_schema(
+        responses={200: serializers.TransportBackendSerializer}
+    )
+    def list(self, request, *args, **kwargs):
+        """Return the list of all defined transport backends."""
+        all_settings = backends.manager.get_all_backend_settings()
+        result = []
+        for name, settings in all_settings.items():
+            serializer = serializers.TransportBackendSerializer(
+                {"name": name, "settings": settings}
+            )
+            result.append(serializer.data)
+        return response.Response(result)
diff --git a/modoboa/urls_api_v2.py b/modoboa/urls_api_v2.py
index 665cd5155..b6376b088 100644
--- a/modoboa/urls_api_v2.py
+++ b/modoboa/urls_api_v2.py
@@ -14,6 +14,7 @@ urlpatterns = [
     path('', include("modoboa.relaydomains.api.v1.urls")),
     path('', include("modoboa.dnstools.api.v2.urls")),
     path('', include("modoboa.maillog.api.v2.urls")),
+    path('', include("modoboa.transport.api.v2.urls")),
 ]
 
 urlpatterns += exts_pool.get_urls(category="api")