On Aug 28, 2004, at 12:09 PM, Paul Iadonisi wrote:
This makes no sense. MAIL FROM is most certainly at least as
available to the MUA as Sender-ID via the Return-Path: header. Neither
is displayed by most MUAs, but if I'm not mistaken, Sender-ID identity
is heuristically determined. Return-Path: is one value, so it is
presumably much simpler to determine.
Your main points are true: In general, the Return-Path and the PRA
value are both in the headers and available to MUAs to display. And
yes, Return-Path requires less processing than the PRA. (Though given
that the headers are read and parsed anyway, PRA isn't that hard.)
However, you are mistaken: There is nothing heuristic in the PRA
identity. It follows directly from the RFC 2822 definition of the
headers. The meanings of From:, Sender:, Resent-From:, and
Resent-Sender: is in there, as is their relative precedence and the
ordering issue with Resent-Sender: and multiple Resent-* blocks.
Anyhow, that may not be significant. It's the only technical
disagreement I have with you that I can discern from your post here.
Ditto here.
- Mark