This seems like a no-brainer, forwarding that joke or virus warning to Aunt Myrtle or to 'everyone you know'. You just press the forward link, put the addresses in to 'To' field and then press send. Right? Wrong! You just made a great big mistake!
So what did you do wrong? Well, maybe several things!
First, never just press forward, enter an email address and send. Why? Because when you just press forward, sometimes that forward is sent as an attachment. Lots of web-based email does that and if you received it as an attachment, the recipient may have to open several attachments before he/she can see the contents. What if one of the previous senders sent along a little 'something extra' like a virus or a worm!
So maybe you aren't sending an attachment, but how many forwards are included in that email? And how many email addresses are included in that 'forwarded' email? (I once counted 138 email addresses in a forwarded email that had been forwarded about 10 times. I knew just one of those folks, the sender who sent it to me! A good thing I'm not a spammer! I hope there wasn't a spammer among any of the other recipients!) Would you want all of those unknown folks to have your email address? Not me!
Second, you should never use the 'To' field unless you are only sending that email to just one person. Use the 'BCC' (Blind Carbon Copy) and the recipient will only see your email address and their own email address.
Just be sure to 'trim' out all of the other email addresses before you press 'Send'.
That 'Send this to everyone you know' is a sure sign that the email is a hoax, urban legend, a political rant or a religious note. Better check first before you send! If it's a virus warning: Virus warning hoax
You may want to think about it; maybe everyone you know doesn't want all those emails.
How a spammer might get all those email addresses in an untrimmed email. They might use a program like Easy Email Extractor!