One source of email addresses for spammers is email messages that have been sent to groups or forwarded from one person to another. Today, I'll talk about how to avoid giving out your friends' email addresses when you email them.

We'll start with forwarding. When someone sends you a message and you forward it to someone else, your email program probably automatically puts something like this in the forwarded message:

> From: "Joe Friend" <joe@friend.com>
> Date: Tue Mar 23, 2004 3:37:44 PM US/Mountain
> To: "Your Name" <your@address.com>
> Subject: Stop SPAM cold!

If you leave that there, you'll be revealing your friend's email address to the person you're forwarding the message to. Maybe they already know your friends address because they know each other. But consider that they may forward the message, including your friend's address to any number of other people, who may forward it, and so on. If you don't delete your friend's address, you never know who will end up adding it to their junk email list.

Aside from the issue of revealing email addresses, it's annoying to have to scroll through lists of everybody who has ever read a message, when they received it, how the subject of the email has or hasn't changed, etc. So just delete that information before sending the message on.

A similar issue arises when you send one message to multiple people. If you list everyone's email address in the "To" or "CC" headers, then everyone else who receives the message will be able to see them. Once again, even if that's okay, they may forward them, and so on, as discussed above. What should you do in this case? List all the recipients addresses in the "BCC" header instead of "To" or "CC". "BCC" stands for "blind carbon copy". Anyone listed there gets a copy without anyone else being able to see their address.