I've done some work for a tzedaka organization at one point and got to see first hand how much money goes to waist on these mailings....we have to put a stop to them! On a typical day I get 5 mailings which all get thrown out and so do many other people. Orginizations have to realize not to spend $10,000 on a mailing only to get back $15,000 which essentialy means 2/3rds of your donation is going towards these mailings!
I don't know if this is how every organization works but this is how it seems to me.