Author name rather than list name for subscribed lists

[Michael Williams <williams@xxxxxxxxxxxxxx>]

Hi,

My .muttrc contains the line "subscribe mutt-users" and no list
commands. From the mutt manual:

  Now that Mutt knows what your mailing lists are, it can do several
  things, the first of which is the ability to show the name of a list
  through which you received a message (i.e., of a subscribed list) in
  the index menu display. This is useful to distinguish between personal
  and list mail in the same mailbox. In the $index_format variable, the
  escape ``%L'' will return the string ``To <list>'' when ``list''
  appears in the ``To'' field, and ``Cc <list>'' when it appears in the
  ``Cc'' field (otherwise it returns the name of the author).

I do not find this behaviour useful, since I use procmail to filter all
my mailing list email into separate mailing boxes. There is therefore no
need to distinguish between personal and list email. How can I disable
this behaviour? I.e. how can I get mutt to display the author name
rather than list name in index view? Is there a simple command to toggle
this behaviour globally, or do I have to change index_format for those
mailboxes in which I keep list email?

Thanks, 
-- Mike