Apply suggestions from code review

Co-authored-by: Patrick Cloke <[email protected]>

docs/usage/configuration/config_documentation.md

@@ -663,8 +663,11 @@ This setting has the following sub-options:
    has missed. Disabled by default.
 * `notif_for_new_users`: Set to false to disable automatic subscription to email
    notifications for new users. Enabled by default.
-* `delay_before_mail`: Time we always wait before ever emailing about a notification
-   (to give the user a chance to respond to other push or notice the window). Defaults to 10 minutes.
+* `delay_before_mail`: The time to wait before emailing about a notification.
+  This gives the user a chance to view the message via push or an open client.
+  Defaults to 10 minutes.
+
+   *New in Synapse 1.98.0._
 * `client_base_url`: Custom URL for client links within the email notifications. By default
    links will be based on "https://matrix.to". (This setting used to be called `riot_base_url`;
    the old name is still supported for backwards-compatibility but is now deprecated.)

synapse/config/emailconfig.py

@@ -294,6 +294,8 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
             self.email_riot_base_url = email_config.get(
                 "client_base_url", email_config.get("riot_base_url", None)
             )
+            # The amount of time we always wait before ever emailing about a notification
+            # (to give the user a chance to respond to other push or notice the window)
             self.delay_before_mail_ms = Config.parse_duration(
                 email_config.get("delay_before_mail", "10m")
             )