One of the I-Cop
members posted a link to this article on Information Week. Fred Langa's article says that (in his test with over 10,000 testers) that only about 60% of non-spam, personal email made it to its intended recipient. Here's the link:
Now if personal email is not getting through, then what makes folks think that their newsletters will get through. Optin, double-optin, CAN SPAM compliant... it doesn't matter. Your mail is being censored!