def default_i18n_subject(interpolations = {}) # :doc:
        mailer_scope = self.class.mailer_name.tr("/", ".")
        I18n.t(:subject, interpolations.merge(scope: [mailer_scope, action_name], default: action_name.humanize))
      end
def default_i18n_subject(interpolations = {}) # :doc:
        mailer_scope = self.class.mailer_name.tr("/", ".")
        I18n.t(:subject, interpolations.merge(scope: [mailer_scope, action_name], default: action_name.humanize))
      end
Translates the +subject+ using Rails I18n class under <tt>[mailer_scope, action_name]</tt> scope.
 If it does not find a translation for the +subject+ under the specified scope it will default to a
 humanized version of the <tt>action_name</tt>.
 If the subject has interpolations, you can pass them through the +interpolations+ parameter.