masses/CORPUS_POLICY

SpamAssassin Corpus Policy
--------------------------

SpamAssassin relies on corpus data to generate optimal scores.  This is
the policy used by all corpora accepted by the SpamAssassin project.

1. All mail must be hand-verified into "spam" and "ham" (non-spam)
   collections.  It may not be solely classified using automated
   spam-classification algorithms such as SpamAssassin and other spam filters.

2. It should not contain old mail.  Older spam uses different techniques and
   legitimate email changes over time as well.  Specifically, please try to
   avoid including spam older than 6 months and ham older than 18 months (12
   months is better).

3. It must contain a representative mix of ham.  That includes commercial ham
   messages, legitimate business discussions, and verified opt-in mail
   newsletters.  This is a very important point!

4. It must not contain certain types of mail to limit corpus bias:

   a. viruses (please check all messages with ClamAV or another anti-virus
      program to exclude these)

   b. anti-spam or anti-virus mailing lists, especially SpamAssassin, that
      frequently include spam and virus elements, even though they are
      technically ham, these often appear to be spam and will skew the
      results, rewriting the tests to avoid triggering on these messages is
      not realistic at this time.

   c. bounces of viruses or spam sent back to forged or faked from addresses,
      (so-called blowback or joe-job bounces), these typically have an
      envelope sender of <> or <MAILER-DAEMON.*>, but please include all valid
      bounces.

   d. mailing list moderation administrative messages that contain spam
      subject lines or excerpts

5. Finally, you should sign an Apache Contributor License Agreement.

Once you run "mass-check" on a corpus, see the instructions in "CORPUS_SUBMIT"
for details of how to verify that the top scorers are not accidental spam that
got through.

lastmod: 2004-09-06 quinlan