Well, tsuwm, I didn't think you were one of the ones that wanted *help...
There are the "email box full" and the "person is not accepting from your address" and the "permanent mailbox failures" and the "person no longer exists" on top of the other, obvious ones (out-of-office, go-to-hell, etc...). What percentage of your email list does get bounced back? My work list runs, on average, from 3-8% depending on how often I edit it. I go by the three bounce back strike rule.
Try making an html based e-mail and embed a .gif or .jpg scan of the wwftd info and note how many of those get returned. A picture may, indeed, be *worth a thousand words.