Action Mailer throwing underscores on template name

I've recently run into a problem with one of my applications that
refuses to send emails using ActionMailer.

Looking at the log, it become obvious what's happening, the system is
looking for templates with underscores at the end. Notice the
exception_notification_ .

For example:
ActionView::ActionViewError (No rhtml, rxml, rjs or delegate template
found for exception_notification_ in /var/rails/nick_warren/releases/
20080303165433/vendor/plugins/exception_notification/lib/../views/
exception_notifier):
    /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.6/lib/action_view/
base.rb:401:in `find_template_extension_for'
    /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.6/lib/action_view/
base.rb:332:in `pick_template_extension'
    /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.6/lib/action_view/
base.rb:249:in `render_file'
    (eval):4:in `render_message'
    /usr/lib/ruby/gems/1.8/gems/actionmailer-1.3.6/lib/action_mailer/
base.rb:424:in `create!'
    /usr/lib/ruby/gems/1.8/gems/actionmailer-1.3.6/lib/action_mailer/
base.rb:385:in `initialize'
    /usr/lib/ruby/gems/1.8/gems/actionmailer-1.3.6/lib/action_mailer/
base.rb:333:in `new'
    /usr/lib/ruby/gems/1.8/gems/actionmailer-1.3.6/lib/action_mailer/
base.rb:333:in `method_missing'
    /var/rails/nick_warren/releases/20080303165433/vendor/plugins/
exception_notification/lib/exception_notifiable.rb:95:in
`rescue_action_in_public'

obviously this comes from the exception notifier plugin:

ExceptionNotifier.deliver_exception_notification(exception, self,
request, data)

Has anybody else seen this? Any ideas on how to get this working?

Thanks,

Andrew

For what it's worth...

First, try using your own ActionMailer model and sending an email, to
see if it fails.

Second, have you updated exception_notification? Do so, especially if
you rails version has changed.

i had a similar problem after using a 3rd party plugin which did some
internationalization things that overrode the actionmailer method for
finding the template so it could append a localization label eg. _uk
or _fr or whatever. Check you haven't got something like that going
on....though i can't see it in the stack trace there.