diff --git a/core/admin/mailu/ui/templates/user/list.html b/core/admin/mailu/ui/templates/user/list.html
index 46638b6b..7d908fe0 100644
--- a/core/admin/mailu/ui/templates/user/list.html
+++ b/core/admin/mailu/ui/templates/user/list.html
@@ -41,7 +41,7 @@
     {% if user.enable_imap %}<span class="label label-info">imap</span>{% endif %}
     {% if user.enable_pop %}<span class="label label-info">pop3</span>{% endif %}
   </td>
-  <td>{{ user.quota_bytes | filesizeformat }}</td>
+  <td>{{ (user.quota_bytes | filesizeformat) if user.quota_bytes else '∞' }}</td>
   <td>{{ user.comment or '-' }}</td>
   <td>{{ user.created_at }}</td>
   <td>{{ user.updated_at or '' }}</td>