diff --git a/docs/content/advanced/mail-forwarding/relay-hosts.md b/docs/content/advanced/mail-forwarding/relay-hosts.md
index b8dfc80c..73b6f339 100644
--- a/docs/content/advanced/mail-forwarding/relay-hosts.md
+++ b/docs/content/advanced/mail-forwarding/relay-hosts.md
@@ -35,6 +35,8 @@ An example configuration file looks like this:
 
 If there is no other configuration, this will cause Postfix to deliver email throught the relay specified in `RELAY_HOST` env variable, authenticating as `relay_user_1` when sent from domain1.com and authenticating as `relay_user_2` when sending from domain2.com.
 
+**NOTE** to activate the configuration you must either restart the container, or you can also trigger an update by modifying a mail account.
+
 ## Sender-dependent Relay Host
 
 Sender dependent relay hosts are configured in `config/postfix-relaymap.cf`. You can create this file manually, or use