Some (re-) submitting system may want to notify receiving system some extra
information about precedence / priority of messages.
Examples
* Forwarders may run spam filters and know submitting message is suspicious
* Postcards/'Send-link-to-friends services may know submitting user is
anonymous or may be forged
* Something else
Extension like
MAIL FROM:<user(_at_)somehost(_dot_)dom>
SUBMITTER:<user(_at_)my_spam_markup_forwarder(_dot_)ru>
EXTRA="junk"
will be (imho) useful in this case
List of available must be reserved (may be JUNK, LIST, SUSPICIOUS,
ANONYMOUS, FIRST-CLASS), usage of extra info may be unspecified, receiving
server can interpret extra info by his own rules and/or reputation services.
Thank you,
Pavel
--
Pavel A. Zavyalov
Yandex Mail project manager
Yandex
http://mail.yandex.ru
http://yandex.ru