Sys.WebForms.PageRequestManagerTimeoutException: The server request timed out.

I saw this problem when i send a mail.The mail button withing a update panel and used a UpdatePanelAnimationExtender. This occured because mail operation relatively long 30 sec or more. What i did, there is a property called AsyncPostBackTimeOut in ScriptManager and set its timeout to 500. Default value is 90.

<asp:ScriptManager ID="ScriptManager1" runat="server" AsyncPostBackTimeout="500">
</asp:ScriptManager>