elmah with customErrors not emailing unless it's a 404 - asp.net-mvc

Question

I am playing around with Elmah to see if I want to use that as my error handling solution. I installed it, hard coded an exception into my page, hit the page wholla! Got my email, everything is happy. However, when I added the customError node to my web.config to redirect to a friendly error page, the email was not sent but I was redirected to my friendly error page.
Strangely, when I browsed to a page that doesn't exist on my site, I was redirected to home (as I set in my customErrors) but I DID receive the email...that could be problematic as I don't want to get a billion emails when people hit my site and add "whatever.php" to the end of the url.
So I have two questions: 1) why would the exception that is being thrown NOT send me an email and 2) how can I tell Elmah NOT to send me emails for 404s?

Answer 1

You can filter things with elmah like such in your Global.asax.cs:
//ELMAH Filtering
protected void ErrorLog_Filtering(object sender, ExceptionFilterEventArgs e)
{
FilterError404(e);
}
protected void ErrorMail_Filtering(object sender, ExceptionFilterEventArgs e)
{
FilterError404(e);
}
//Dimiss 404 errors for ELMAH
private void FilterError404(ExceptionFilterEventArgs e)
{
if (e.Exception.GetBaseException() is HttpException)
{
HttpException ex = (HttpException)e.Exception.GetBaseException();
if (ex.GetHttpCode() == 404)
{
e.Dismiss();
}
}
}
So add the call to FilterError404 to any part of the filtering. The above example will have it filter 404 for both ErrorLog and Email. Also check out:
http://code.google.com/p/elmah/wiki/ErrorFiltering
You can also do Filtering By Source as described in the link:
<elmah>
...
<errorFilter>
<test>
<and>
<equal binding="HttpStatusCode" value="404" type="Int32" />
<regex binding="FilterSourceType.Name" pattern="mail" />
</and>
</test>
</errorFilter>
</elmah>
Check web.config:
<?xml version="1.0" encoding="UTF-8"?>
<!--
Note: As an alternative to hand editing this file you can use the
web admin tool to configure settings for your application. Use
the Website->Asp.Net Configuration option in Visual Studio.
A full list of settings and comments can be found in
machine.config.comments usually located in
\Windows\Microsoft.Net\Framework\v2.x\Config
-->
<configuration>
<configSections>
<sectionGroup name="elmah">
<section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah" />
<section name="errorLog" requirePermission="false" type="Elmah.ErrorLogSectionHandler, Elmah" />
<section name="errorMail" requirePermission="false" type="Elmah.ErrorMailSectionHandler, Elmah" />
<section name="errorFilter" requirePermission="false" type="Elmah.ErrorFilterSectionHandler, Elmah" />
</sectionGroup>
</configSections>
<appSettings />
<!-- ELMAH: Configuration -->
<elmah>
<security allowRemoteAccess="1" />
<errorLog type="Elmah.SqlErrorLog, Elmah" connectionStringName="Elmah.Sql" />
<errorMail defaultCredentials="true" from="someuser#example.com" to="someuser#example.com, someuser2#example.com" subject="Error (STAGING): {0}" async="true" smtpPort="25" smtpServer="192.168.1.1" userName="smtpUserName" password="smtpPassword" />
</elmah>
<connectionStrings>
<add name="Elmah.Sql" connectionString="Data Source=192.168.1.1;database=DBName;integrated security=false;User ID=MyUserName;Password=MyPassword" />
</connectionStrings>
<system.net>
<mailSettings>
<smtp deliveryMethod="Network" from="someuser#example.com">
<network defaultCredentials="true" host="192.168.1.1" port="25" userName="smtpUserName" password="smtpPassword" />
</smtp>
<!-- Use this setting for development
<smtp deliveryMethod="SpecifiedPickupDirectory">
<specifiedPickupDirectory pickupDirectoryLocation="C:\Temp" />
</smtp>
-->
</mailSettings>
</system.net>
<system.web>
<!--
Set compilation debug="true" to insert debugging
symbols into the compiled page. Because this
affects performance, set this value to true only
during development.
-->
<compilation debug="true">
<assemblies>
...........................
</assemblies>
</compilation>
.......................
<!--
The <customErrors> section enables configuration
of what to do if/when an unhandled error occurs
during the execution of a request. Specifically,
it enables developers to configure html error pages
to be displayed in place of a error stack trace.
-->
<customErrors mode="RemoteOnly" defaultRedirect="~/Home/MyErrorPage" />
.............................
<httpHandlers>
..............................
<!--ELMAH-->
<add verb="POST,GET,HEAD" path="/MyErrorPage/elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" />
</httpHandlers>
<httpModules>
........................
<!-- ELMAH: Logging module -->
<add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" />
<add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" />
</httpModules>
</system.web>
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
<modules runAllManagedModulesForAllRequests="true">
.............................
<!-- ELMAH-->
<add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" />
<add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" />
<add name="ErrorFilter" type="Elmah.ErrorFilterModule, Elmah" />
</modules>
<handlers>
..............
<!--ELMAH-->
<add name="Elmah" verb="POST,GET,HEAD" path="/MyErrorPage/elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" />
</handlers>
</system.webServer>
..................
</configuration>
FYI: NuGET Package also available as explained by Scott Hanselman:
http://www.hanselman.com/blog/NuGetPackageOfTheWeek7ELMAHErrorLoggingModulesAndHandlersWithSQLServerCompact.aspx