instance method set_status

# File actionmailer/lib/action_mailer/vendor/tmail-1.2.3/tmail/port.rb, line 197
    def set_status( tag, flag )
      begin
        tmpfile = @filename + '.tmailtmp.' + $$.to_s
        File.open(tmpfile, 'w') {|f|
          write_status f, tag, flag
        }
        File.unlink @filename
        File.link tmpfile, @filename
      ensure
        File.unlink tmpfile
      end
    end