diff --git a/frontend/src/api/accounts.js b/frontend/src/api/accounts.js
index c04b97ce5..f0e4902cf 100644
--- a/frontend/src/api/accounts.js
+++ b/frontend/src/api/accounts.js
@@ -17,6 +17,9 @@ export default {
   getRandomPassword() {
     return repository.get(`${resource}/random_password/`)
   },
+  getCredentials(accountId) {
+    return repository.get(`credentials/${accountId}/`, { responseType: 'blob' })
+  },
   validate(data) {
     return repository.post(`${resource}/validate/`, data)
   },
diff --git a/frontend/src/components/admin/identities/IdentityList.vue b/frontend/src/components/admin/identities/IdentityList.vue
index fcb23d18c..1591bc92a 100644
--- a/frontend/src/components/admin/identities/IdentityList.vue
+++ b/frontend/src/components/admin/identities/IdentityList.vue
@@ -362,9 +362,9 @@ function getMenuItems(item) {
       result.push({
         label: element.label,
         icon: element.icon,
-        onClick: () => {
-          if (element.type === 'download') {
-            //TODO : downloadFile(element)
+        onClick: (account) => {
+          if (element.name === 'get_credentials') {
+            downloadCredentials(account)
           }
           fetchIdentities()
         },
@@ -438,6 +438,16 @@ async function deleteAccount(account) {
   }
 }
 
+async function downloadCredentials(account) {
+  const resp = await accountsApi.getCredentials(account.pk)
+  const blob = new Blob([resp.data], { type: resp.headers['Content-Type'] })
+  const link = document.createElement('a')
+  link.href = URL.createObjectURL(blob)
+  link.download = `credentials_${account.pk}.pdf`
+  link.click()
+  URL.revokeObjectURL(link.href)
+}
+
 function editAlias() {}
 
 function deleteIdentities() {}
diff --git a/modoboa/pdfcredentials/api/v2/serializers.py b/modoboa/pdfcredentials/api/v2/serializers.py
index 502657b08..49d0625b4 100644
--- a/modoboa/pdfcredentials/api/v2/serializers.py
+++ b/modoboa/pdfcredentials/api/v2/serializers.py
@@ -38,12 +38,16 @@ class PDFCredentialsSettingsSerializer(serializers.Serializer):
         required=False, allow_blank=True, allow_null=True
     )
     include_connection_settings = serializers.BooleanField(default=False)
-    smtp_server_address = serializers.CharField()
+    smtp_server_address = serializers.CharField(
+        required=False, allow_blank=True, allow_null=True
+    )
     smtp_server_port = serializers.IntegerField(default=587)
     smtp_connection_security = serializers.ChoiceField(
         choices=CONNECTION_SECURITY_MODES, default="starttls"
     )
-    imap_server_address = serializers.CharField()
+    imap_server_address = serializers.CharField(
+        required=False, allow_blank=True, allow_null=True
+    )
     imap_server_port = serializers.IntegerField(default=143)
     imap_connection_security = serializers.ChoiceField(
         choices=CONNECTION_SECURITY_MODES, default="starttls"
@@ -72,13 +76,21 @@ class PDFCredentialsSettingsSerializer(serializers.Serializer):
             enabled_pdfcredentials is None
             and param_tools.get_global_parameter("enabled_pdfcredentials")
         )
+        errors = {}
         if condition:
             storage_dir = data.get("storage_dir", None)
             if storage_dir is not None:
                 if not os.path.isdir(storage_dir):
-                    raise serializers.ValidationError(_("Directory not found."))
-                if not os.access(storage_dir, os.W_OK):
-                    raise serializers.ValidationError(_("Directory is not writable"))
+                    errors["storage_dir"] = _("Directory not found.")
+                elif not os.access(storage_dir, os.W_OK):
+                    errors["storage_dir"] = _("Directory is not writable")
+            include_connection_settings = data.get("include_connection_settings")
+            if include_connection_settings:
+                for field in ["smtp_server_address", "imap_server_address"]:
+                    if not data.get(field):
+                        errors[field] = _("This field is required.")
+        if errors:
+            raise serializers.ValidationError(errors)
         return data
 
 
diff --git a/modoboa/pdfcredentials/api/v2/tests.py b/modoboa/pdfcredentials/api/v2/tests.py
index f0ac8a2dd..ac121f451 100644
--- a/modoboa/pdfcredentials/api/v2/tests.py
+++ b/modoboa/pdfcredentials/api/v2/tests.py
@@ -190,3 +190,31 @@ class PDFCredentialViewTestCase(ModoAPITestCase):
         data["enabled_pdfcredentials"] = False
         resp = self.client.put(url, data, format="json")
         self.assertEqual(resp.status_code, 200)
+
+    def test_optional_settings(self):
+        url = reverse("v2:parameter-global-detail", args=["pdfcredentials"])
+        path = f"{self.workdir}/credentials"
+        os.makedirs(path)
+        data = {
+            "enabled_pdfcredentials": True,
+            "storage_dir": path,
+            "webpanel_url": "http://localhost",
+        }
+        resp = self.client.put(url, data, format="json")
+        self.assertEqual(resp.status_code, 200)
+
+        data["include_connection_settings"] = True
+        resp = self.client.put(url, data, format="json")
+        self.assertEqual(resp.status_code, 400)
+        errors = resp.json()
+        self.assertEqual(errors["smtp_server_address"][0], "This field is required.")
+        self.assertEqual(errors["imap_server_address"][0], "This field is required.")
+
+        data.update(
+            {
+                "smtp_server_address": "mail.localhost",
+                "imap_server_address": "mail.localhost",
+            }
+        )
+        resp = self.client.put(url, data, format="json")
+        self.assertEqual(resp.status_code, 200)
diff --git a/modoboa/pdfcredentials/app_settings.py b/modoboa/pdfcredentials/app_settings.py
index 4f2efeade..ea54d6405 100644
--- a/modoboa/pdfcredentials/app_settings.py
+++ b/modoboa/pdfcredentials/app_settings.py
@@ -121,7 +121,7 @@ PDF_CREDENTIALS_PARAMETERS_STRUCT = collections.OrderedDict(
                             "smtp_server_address",
                             {
                                 "label": _("SMTP server address"),
-                                "display": "include_connection_settings=True",
+                                "display": "include_connection_settings=true",
                                 "help_text": _(
                                     "Address of the SMTP server (hostname or IP)"
                                 ),