Redirect and Display meesage

I have one page Passwordchange.aspx
in this when I change password and click ok button means it has redirect to 
./Common/Main.aspxmy requriment is after redirect to Main.aspx and display alert message I tried like this but not working, please help. ScriptManager.RegisterStartupScript(this, GetType(), "alert", "alert('Password changed sucessfully. But notification mail couldn’t be sent to you because of invalid email. Please change your email.');window.location = '../Common/Main.aspx';", true);