On Wed, Sep 14, 2016 at 5:52 PM, Lyndon Nerenberg <lyn...@orthanc.ca> wrote:
> Not the standard, but a convention.
>
> The standard is documented in RFC 5322 section 3.6.4 (and dates back to
> RFC822).

I think you may mean RFC 5322 section 3.6.5, which does give a "MAY"
suggestion for the use of "Re: " at the start of the contents of the
subject field, but I'm unable to find any mention of the square
bracket or "was" convention for subject line changes within a thread
anywhere in RFC 5322, RFC 822, or even RFC 733.  Aside from the "Re: "
convention, all three RFCs describe the Subject field as unstructured
text, subject to the line folding rules (defined in RFC 5322 section
2.2.3 "Long Header Fields").

Reply via email to