[Greg Ward]
> Case of headers is definitely helpful.  SpamAssassin has a rule for it
> -- if you have headers like "DATE" or "SUBJECT", you get a few more
> points.Across my data, all-caps DATE, SUBJECT, TO, etc indeed appear only in the
spam collections.  OTOH, they don't appear often -- less than 1% of spam
messages have at least one of these all-cap header lines.  But when I'm
fighting what are now sub-1% f-n rates, even rare clues can help!