diff --git a/README.md b/README.md
index bc1b058..b09b40e 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# mailGraph
+# mailGraph (v1.17)
 Zabbix Media module and scripts for sending e-mail alerts with graphs.
 
 [![](images/Example-mail-message.png?raw=true)](images/Example-mail-message.png)
@@ -51,6 +51,8 @@ I've tested my code with Zabbix 5.0.5 (LTS) on Linux with local Postfix. Not sur
 
 **"mail_from"** must be a valid e-mail address which represents the 'from' address in the mails that are sent (ie. "zabbix.mailgraph.noreply@domain.com") that is acceptable by your mail server.
 
+**"period"** must be a valid Zabbix period (like "1d", "1w" or "48h") that will be applied to the graph. Default is "48h" when not specified.
+
 # Load the Media Type "MailGraph" into Zabbix
 - Login to your Zabbix instance
 - Goto "Administration" => "Media yypes"