Add user mailer from spree_auth_devise
user
```ruby
module Spree
  class UserMailer < BaseMailer
    def reset_password_instructions(user)
      recipient = user.respond_to?(:id) ? user : Spree.user_class.find(user)
      @edit_password_reset_url = spree.edit_spree_user_password_url(:reset_password_token => recipient.reset_password_token)

      mail(:to => recipient.email, :from => from_address,
          :subject => Spree::Config[:site_name] + ' ' + 
            I18n.t(:subject, :scope => [:devise, :mailer, :reset_password_instructions]))
    end
  end
end
```
assistant