http://www.mail-archive.com/faq.html#spam
What about spamming?
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The Mail Archive utilizes two levels of electronic countermeasures to prevent spam incidents. First, we explicitly block spam harvesting robots (spambots) from accessing our server. We deny access, at the server level, for any software that matches the browser ID of a known spambot. For more information about blocking spambots at the server level, see Dr. Charles Brabec's anti-spambot guidelines. Our second line of defense is to make sure that the web pages themselves are spambot resistant. We do not use any unshielded mailto: hyperlinks, email addresses and we strip out, scramble, or obfuscate all email addresses from message headers and bodies. Yet we still provide a way for people to reply to an archived message, using their regular email software. This feat is achieved with a special POST protected CGI gateway which returns a mailto: URL to the user agent. This technique is extremely effective in blocking spam harvesting robots; for more information, see Mullane's Spambot Beware guide. The effectiveness of our spam-blocking preventative measures are monitored by spambot trap addresses like honeypot at jab.org.
Despite all these steps, recognize that any time an email address is exposed on the internet, spammers could potentially abuse it. Open mailing lists are vulnerable to spam attacks. Thus there is some risk associated with using the Mail Archive, and we do not assume any legal liability for spammers. Suggestions or feedback regarding privacy or anti-spamming enhancements are appreciated.