diff --git a/doc/ADMIN.md b/doc/ADMIN.md
index 2094e6a..5dd1161 100644
--- a/doc/ADMIN.md
+++ b/doc/ADMIN.md
@@ -1 +1,3 @@
-If you wish, you can add custom configurations inside `__INSTALL_DIR__/config.local.php`.
\ No newline at end of file
+If you wish, you can add custom configurations inside `__INSTALL_DIR__/config.local.php`.
+
+For more than one instance, each will need a dedicated domain name for mail configuration, for example: domain.tld/paheko, paheko.domain.tld, paheko2.domain.tld