Best ways to reduct volume when emailing unhandled exception

I'm thinking of adding some code to my global.asax to my web apps to email me when there is an unhandled exception.

Current, I'm doing the following

• Writing a cookie on the user's machine - in case they spam hit F5 and the website was restarted
• Adding an entry into system.Web.Cache -

Am I missing something? Would you do something different?

protected void Application_Error()
{
    var ex = Server.GetLastError();
    Serv开发者_运维技巧er.ClearError();

    if (NotInCache(ex))
    {
        // Email support
    }
}



private static bool NotInCache(Exception ex)
{
    bool returnValue = true;

        if (ex != null)
        {
            HttpContext current = HttpContext.Current;
            LogWriter.Trace(MethodBase.GetCurrentMethod(), Dfait.Diagnostics.TraceLevel.Level4, "Checking Cache for our exception");

            if (current != null)
            {
                string key = ex.StackTrace;
                string[] split = System.Text.RegularExpressions.Regex.Split(ex.StackTrace, "\r\n");
                string value = "Exception Exists";
                DateTime expiryDate = DateTime.Now.AddDays(1);

                if (split.Length > 0)
                {
                    key = split[0];
                }

                key = key.Trim();

                HttpCookie remedyCookie = current.Request.Cookies[key];

                if (remedyCookie == null)
                {
                    HttpCookie newCookie = new HttpCookie(key, value);
                    newCookie.Expires = expiryDate;
                    current.Response.Cookies.Add(newCookie);
                }
                else
                {
                    returnValue = false;
                }

                // The next block is to check the cache of the user.
                object foundCache = HttpRuntime.Cache[key];

                if (foundCache == null)
                {
                    HttpRuntime.Cache.Insert(key, value, null, expiryDate, TimeSpan.Zero);
                }
                else
                {
                    returnValue = false;
                }
            }
        }

    return returnValue;
}

Depending on how soon you want the exceptions you could always just log them to a file and then email the file to yourself every 10 minutes, 1 hour, 1 day and etc.

That way you don't need to worry to much about if people spam the website as it will just be a bunch of duplicate exceptions in the file.

Once you send the file you could delete it or some how mark it as sent and then start a new file that way you only get a file emailed once there is something new to be sent.

Personally I wouldn't go about fixing the problem the way you are suggesting. You're better off getting emailed every single exception and then finding a nice way of filtering the emails as they come in.

I have a similar process setup using Elmah (you should look into using it) and I can tell you know that if I had a filter like you're suggesting, I would have missed out on important information to help diagnose problems.

What I'm saying is that it will end up swallowing some exceptions you didn't want it to.

Also, I can tell you first hand that you're going to get spammed by the unhandled exceptions anyway. The amount of unhandled exceptions that occur from numerous hacker vulnerability spiders and even search bots will have your inbox overflowing in no time.