<p>I followed this <a href="http://svn.rubyonrails.org/rails/plugins/exception_notification/README" rel="nofollow noreferrer">tutorial</a> on configuring the Rails plugin ExceptionNotifier.</p>

<p>I know that I have ActionMailer configured correctly because I am getting mail from other forms. I even have local_addresses.clear set so that it should be delivering mail no matter what.</p>

<p>I am using Apache with a mongrel_cluster running in the backend.</p>

<p>What am I missing?</p>

You're using the SVN version of the plugin, which is probably unmaintained.
Latest version can be found here
.
Second thing which you can do is check the production log. Mailings get written to the log, so you'll see if Rails ever even
tried
to send it. If there are no entries, that means things are silently failing, which probably happens because -- for some reason -- exceptions are not caught properly.