We have been having a problem with legitimate mail to several of our larger lists (10,000+ subscribers) being mistaken as spam by our mail system's spam filter. 

Has anyone experienced this type of thing with large lists, or does anyone have suggestions on what to do?

We have raised the junk mail score threshhold and that has helped. But I'm wondering if there might be a way to make the list mail less spammy, so it doesn't get as high a score in the first place.
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Tom Kozma
Computing & Information Technology
Wayne State University, Detroit MI