# File /Users/nshb/svn/svn.inimit.com/railsmanual.com/www/trunk/src/rails-2.0.1/actionmailer/lib/action_mailer/vendor/tmail-1.1.0/tmail/interface.rb, line 82
    def addrs2specs( addrs )
      return nil unless addrs
      list = addrs.map {|addr|
          if addr.address_group?
          then addr.map {|a| a.spec }
          else addr.spec
          end
      }.flatten
      return nil if list.empty?
      list
    end