Actually, Mr. Cook, the standard for the last 35 years or so has been to
change the subject line, with the old subject in SQUARE BRACKETS with the
characters "was: " prepended.
Not the standard, but a convention.
The standard is documented in RFC 5322 section 3.6.4 (and dates back to
RFC822). This isn't anything new. In the Usenet world, nn and trn made
agressive use of these headers to thread discussion chains. Any good MUA
will use them as well. Note that in the email world, 'popular' and 'good'
are mostly disjoint sets :-(
--lyndon
