"Dick St.Peters" <stpeters(_at_)NetHeaven(_dot_)com> writes:
It logs the result of each check, so I have thousands of log entries
reporting both checks. 1000 messages for which SPF or Sender-ID
yielded a definitive pass or fail would typically include only about
10-20 for which they disagreed. When they did, the one saying "pass"
was nearly always right.
Can you give some more details here? When/why were the SPF and SID
checks different? Which one was right most of the time?
The cases where SPF said pass and SID said fail were mostly mailing
lists that did not insert a PRA-changing header but did use a
The cases where SID said pass but SPF said fail were mostly mail from
special-case mailers such as website CGIs at sites that had forgotten
their web servers send mail when making their SPF records.
Obviously these are fixable at the sending sites.
I want to emphasize again that nearly all spam is eliminated before
mail even gets to my milters, meaning 80+% of smtp connections are
never processed for SPF or SID. If the SID and SPF checks were done
up front on all mail, the results would probably be very different.
Also, my results were gradually distorted by my own actions. For
example, on being identified, mailing list mailers were added to the
"do not process" exception list.
Dick St.Peters, stpeters(_at_)NetHeaven(_dot_)com