mailers.rb

if Rails.application.config.action_mailer.show_previews
  Rails::MailersController.class_eval do
    include AdminWebAuthenticatable
  end
end

module AdminWebAuthenticatable
  extend ActiveSupport::Concern
  included do
    before_action :require_user!
    helper_method :current_user
    helper_method :current_admin
    rescue_from NotAuthorizedException, with: -> { redirect_to root_path }
  end
  
  # Truncated
end