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You only have to sign up and log in when posting data to the site or subscribing to a mailing list.
Your information will NEVER be given out to a third party unless there is an extreme circumstance. The only time such a circumstance came up was when the United States Secret Service asked for information on a subscriber to a mailing list. The reason was that the subscriber posted a message with the subject of "Kill the President". This was a mistake and he both apologized to the list and cleared it all up with the government. Other than that, no information has ever been given out.
If you have subscribed to a mailing list, the option to leave the list is posted on the bottom of EVERY message.
We have a VERY strict anti-spam policy with custom filters applied to all lists.