Log4r configurator throws exception instantiating EmailOutputter

I'm setting up Log4r using an XML configuration file, and I can't get the EmailOutputter to work correctly. Here's my outputter tag:

<outputter type="EmailOutputter" name="exception_email" trunc="false" level="ERROR" buffsize="10">
        <formatter type="PatternFormatter" pattern="#{pattern}"/>
        <server>#{smtp_address}</server>
        <port>#{smtp_port}</port>
        <domain>#{smtp_domain}</domain>
        <from>logging@#{smtp_domain}</from>
        <to>exceptions@mydomain.com</to>
        <subject>Log Report</subject>
        <immediate_at>ERROR, FATAL</immediate_at>
      </outputter>

I've triple and quadruple checked that all the XML variables are being passed in correctly using the RubyMine step-through debugger. The exception message is:

Uncaught exception: Problem creating outputter: uninitialized constant Log4r::Configurator::EmailOutputter /usr/local/lib/ruby/gems/1.9.1/gems/log4r-1.1.10/lib/log4r/configurator.rb:87:in block in decode_xml' /usr/local/lib/ruby/1.9.1/rexml/element.rb:905:inblock in each' /usr/local/lib/ruby/1.9.1/rexml/xpath.rb:67:in each' /usr/local/lib/ruby/1.9.1/rexml/xpath.rb:67:ineach' /usr/local/lib/ruby/1.9.1/rexml/element.rb:905:in each' /usr/local/lib/ruby/gems/1.9.1/gems/log4r-1.1.10/lib/log4r/configurator.rb:87:indecode_xml' /usr/local/lib/ruby/gems/1.9.1/gems/log4r-1.1.10/lib/log4r/configurator.rb:82:in actual_load' /usr/local/lib/ruby/gems/1.9.1/gems/log4r-1.1.10/lib/log4r/configurator.rb:56:inload_xml_file' /root/src/upside/common/upside_logger.rb:16:in initialize' /root/src/upside/common/logger_factory.rb:7:innew' /root/src/upside/common/logger_factory.rb:7:in new_logger' /root/src/upside/config/application.rb:30:inblock in ' /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/lazy_load_hooks.rb:34:in call' /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/lazy_load_hooks.rb:34:inexecute_hook' /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/lazy_load_hooks.rb:26:in block in on_load' /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/lazy_load_hooks.rb:25:ineach' /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/lazy_load_hooks.rb:25:in on_load' /usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/railtie/configuration.rb:43:inbefore_configuration' /root/src/upside/config/application.rb:29:in <class:Application>' /root/src/upside/config/application.rb:15:in' /root/src/upside/config/application.rb:14:in <top (required)>' /usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands.rb:53:inrequire' /usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands.rb:53:in block in <top (required)>' /usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands.rb:50:intap' /usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands.rb:50:in <top (required)>' /root/src/upside/script/rails:6:inrequire' /root/src/upside/script/rails:6:in `'

I've double checked the gem installation and the emailoutputter.rb is in the correct directory with the other outputters (which function correctly).

Thanks!

I found that the log4r file lib/log4r.rb to be missing the line require "log4r/outputter/emailoutputter". Adding this missing require to my Rails application in a config/initializer file allowed the EmailOutputter class available.