Your basic problem is that Cousin Bob is somewhat of a twit when it comes to email. I've had similar things happen when liberal friends send me stupid email..... If they're dumb enough to publish their friends' email addresses, I'll gladly supply 'em all with a dose of the truth.
When you want to send a message to a list of people, put their email address in the "bcc" field. BCC is blind carbon copy. Nobody sees the email addresses there. Just put one person's address (even your own) in the "To:" field the rest in the bcc field and send the email.
Everyone gets the eamil and no one sees the email addresses.
I use BCC routinely when sending to a group to keep email addresses confidential. Note that you do not need to include anyone in the TO: field when you do this (at least not in Outlook Express).