url referrer problem in gmail

Question

Hi , I am getting Url referer in global asax file.

 try
    {
        if (Session["url"] == null && !Request.UrlReferrer.ToString().StartsWith("http://www.mydomain") && !Request.UrlReferrer.ToString().StartsWith("http://mydomain"))
            Session["Url"] = Request.UrlReferrer;
    }
    catch { }

Its working, but if the url in gmail dosent work. How canI get Url Referrer from gmail? Thanks