diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 7136205b75..6b3f808c6a 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -667,6 +667,12 @@ There are a number of settings available on `config.action_mailer`:
     config.action_mailer.interceptors = ["MailInterceptor"]
     ```
 
+* `config.action_mailer.preview_interceptors` registers interceptors which will be called before mail is previewed.
+
+    ```ruby
+    config.action_mailer.preview_interceptors = ["MyPreviewMailInterceptor"]
+    ```
+
 * `config.action_mailer.preview_path` specifies the location of mailer previews.
 
     ```ruby