Not sure of this, Mark probably knows, but a list like this is basically an email address that receives mail and reflects it back out to a subscriber list. This is what allows the contents to be archived and searchable. The key here is how to manage search-ability. I agree, sometimes searching is a real pain because you might search for a key phrase and get 50+ matches but when it comes down to it, there were only 8 unique replies, the rest were quoted text.
A solution on the back end might be to use a search engine that is capable of ignoring quoted text but telling a search engine how to identify quoted text might prove difficult as not all email clients treat (set a marker) quoted text the same way and end users can use their own methods that will throw off the search. If that could be done then searching would again be a worthwhile endeavor. Writing a search engine this flexible/intelligent would be a cool project, I'm sure there are some out there, but I've had my fill of recreating the wheel. I have no idea how flexible the search engine currently in use is, but the question could be asked. Another solution on the back end would be to filter all the email as it comes in and strip all incoming traffic by certain definable rules. Again this would involve a marker of some sort to identify quoted text. This would be the better of the two as the messages going into the database would be smaller to begin with. This in turn would make searches faster too. So you either strip it as it comes in, or you ignore it during a search, or you just abide by the current rules and whack the quoted text out when you write it. The burden of keeping the database productive has to fall somewhere. My $0.02 Phill Hill Collinsville, IL