Editing Anti-spam techniques (section)

===Ham passwords===
Systems that use "ham passwords" ask unrecognised senders to include in their email a password that demonstrates that the email message is a "ham" (not spam) message. Typically the email address and ham password would be described on a web page, and the ham password would be included in the subject line of an email message (or appended to the "username" part of the email address using the "[[Email address#Address tags|plus addressing]]" technique). Ham passwords are often combined with filtering systems which let through only those messages that have identified themselves as "ham".<ref name="ham">David A. Wheeler, (May 11, 2011) [http://www.dwheeler.com/essays/spam-email-password.html Countering Spam by Using Ham Passwords (Email Passwords)] {{webarchive|url=https://web.archive.org/web/20120204050500/http://www.dwheeler.com/essays/spam-email-password.html |date=2012-02-04 }}</ref>