Including partials in ActionMailer template files?

I have class called:

class Notifier < ActionMailer::Base

Then in my view for that class I have an rhtml file that holds the html
for the email. I am trying to do

<%= render :partial => “header” %>

and I’m getting:

ActionView::TemplateError (undefined method `controller_path’ for
Notifier:Class) on line #1 of

Any idea how I can include partials in these files?

Thanks for your help.