When people send email in a single message to me and many other people they know, I'd like them to use BCC, not TO or CC, since my email address is usually none of those other recipients' business. Of course, many people don't have the netiquette habits to do this. When I get one of these group emails, I politely ask the sender to either use BCC from now on or to take me off their mailing list or out of their address book. I usually get a "sorry, ok" reply, but they tend to forget, so they sometimes do it again. Even if they learn the lesson, somebody else will be next to do it the wrong way. It occurs to me that when people make a common mistake, software can help. Wouldn't it be a good idea if Mac Mail and other email clients warned you, by default, if you put more than 2 people in the TO or CC field? They could pop up a message like "For the privacy of recipients, would you like to move these lists into the BCC field?" Users could either click "Yes" or "No". Those of us who don't need it could disable the warning in the application preferences and never see this warning. But for others it might be just the thing, the same way a good email program should warn you if you leave the Subject field blank. I think this feature might help people who value their privacy from strangers and even help the people who make this common netiquette mistake. Anybody else think so?