Usually junkmailers get your address from finding it on a list of addresses in a forwarded message.
For example: your friend email@example.com forwards a joke to you and 10 other people without removing the headers from the person that forwarded it to him. Now, you get the message with about 10 eMail addresses before the actual message. You read the message and delete it without forwarding it. However, when Tony forwarded the message to you, Suzie@anotherdomain.com also got the message because Tony put BOTH suzie's and your address in the TO: or CC: field. Now Suzie forwards the message to 10 of her friends without removing the headers. The message she forwards still contains the 10 addresses she got it with, along with YOUR address. Those 10 people forward it on and now your Email address is in hundreds of messages floating around the Internet.
Eventually one of these messages gets in the hands of a spammer (with a huge list of known FRESH Email addresses) and he adds it to spam lists for sale.
Junkmailers sometimes originate messages,
such as virus hoaxes, chain letters, etc. that they know will get
forwarded around so that they can get some fresh addresses when copies
of the message eventually get sent back to them.
How do you prevent this? If someone forwards jokes and/or other messages that are expected to be forwarded around, ask that person to use BCC: (Blind Carbon Copy) for the addresses they are forwarding the message to. If they don't your Email address WILL eventually end up on a junkmail list, even if you personally never forward one of those messages!
If you want to forward a message to multiple recipients, please remove all
the EMail addresses from the top of the message and always use BCC for all the
recipients. This will hide and protect the Email addresses of your friends.
Any message that is to YOU ONLY is fine to have your address in the "TO:" field but messages that may get forwarded to others should follow the guidelines listed below.
If you change your Email address I would recommend sending all of your friends who forward messages something similar to this:
Because of all the spam mail that we have been receiving, we have changed our e-mail address.
This applies to any type of forwarded, multiple addressed e-mail such as Jokes and other forwards. We love receiving them, but they have been known to accumulate large lists of Email addresses that eventually end up in the wrong hands.
When you want to send/forward a message to multiple people:
1. Use a fake name for the "to:" section (example JOHNDOE@NOWHERE.COM)
2. Enter the Email addresses of the people you want to send your message to under the BCC: section instead of TO: or CC:
(BCC stands for "Blind Carbon Copy")
You should also remove the headers from previous forwards containing other people's Email addresses.
This will prevent spammers from getting and spamming our e-mail addresses.
There are some programs to help manage spam such as Mailwasher