Dear Harry: I just read an article that stated that most charitable organizations share their mailing lists with other charities on some type of reciprocal arrangement. Perhaps this explains why I get several mailings from the same organization, sometimes within the same week. This is really a burden to me as well as to the post office. It adds to the cost of mail to all of us because many of these groups get favored mailing rates that do not cover the costs. And this does not even consider the cost of the solicitation literature. Sometimes these duplicate mailings cause me to err and make more than one contribution to the same charity. There has to be some way they can screen their mailings to avoid this. Until that's done, is there a way I can get my own mail cleaned up?

What Harry says: I fully sympathize with your position. More than once, I have made extra contributions because of the sharing of lists. Of course, since it's for a good cause, I'm not overly upset. What is most disturbing to me is that many charities will make their mailing lists available to commercial enterprises for a rental fee. While this may add to the charity's coffers, I get a very uncomfortable ethical feeling. If you want to make an effort to reduce the duplicates and the rental of lists, put a note in with your contribution to that effect. *

Write Harry Gross c/o the Daily News, 400 N. Broad St., Philadelphia, PA 19130. Harry urges all his readers to give blood - contact the American Red Cross at 800-GIVE LIFE.