Whether you're using the mail to pitch a product or appeal for help, it can be hard to know how much information to send along. Send too little material and it becomes meaningless, but send too much, and your prospect might not read it. Instead of either/or, how about both/and? Highlight key points in yellow, suggests David Yoho, president of The Professional Educators Group (who follows his own advice).
Yoho doesn't suggest trying to make an entire sale by mail. The highlights should serve as a hook -- enough of one that prospects will get on the phone when you follow your mailing with a call. Your prospects may never read your entire packet, or they may not read it until after you've talked. But at least they knows that it's there, and that there's substance to back up your highlighted claims.