Mailer multiparts order , :parts_order doing nothin ..

I am sending multiparts emails ( html and plain text ) , I wrote as
default :

default :from => Rails.configuration.no_reply_address, :parts_order =>
["text/html", "text/enriched", "text/plain" ]

and each email is generated with the 2 formats :

       mail(:to => @sender, :subject => "#{I18n.t(:email_upload)}") do

format>

          format.html {render :template => @template }
          format.text {render :layout => false, :template =>
@template}
      end

I receive both , but it's always the plain_text which is the first to
display ( on my Mac, w Mail.app I have to ask for the alternative to
see the html version ..)

did I miss anything important ?

thanks fyh