subject mungeing and header question

I'm using mutt as a mail reader, and I love the message threading.
The largest mailing list I belong to has just instituted a bunch of changes,
and I now have a mess.  NONE of the messages will thread anymore.

Is this because there is no InReplyTo header in these messages anymore,
or is it because they are mungeing the subject header by pre-pending
[911] in front of every message subject?

If the latter, can procmail help me out here by stripping [911] from the 
front of each subject, allowing mutt to thread the messages based on the
subject line content?  If so, how would I go about re-writing the subject
line?

thanks,
-chuck

-- 
ACCEL Services, Inc.| Specialists in Gravity, Magnetics |  1(713)993-0671 ph.
1980 Post Oak Blvd. |   and Integrated Interpretation   |  1(713)960-1157 fax
    Suite 2050      |                                   |
 Houston, TX, 77056 |          Chuck Campbell           | 
campbell(_at_)neosoft(_dot_)com
                    |  President & Senior Geoscientist  |

     "Integration means more than having all the maps at the same scale!"