[Mimedefang] Deadline for SPF records *long w/morbid horoscope*

[Kevin A. McGrail]

> If the receiving MX servers always knew all valid recipient addresses
> *at (E)SMTP connection time*, then there would be no bounces...only
> rejections.
>
> This solves the problem without introducing anything new to (E)SMTP.

At the core, this solution ignores the concept and purpose of a backup MX
which is a reality and necessity for many companies where email is critical.
I also believe moving towards publishing valid email lists (even privately)
as in the do-not-email list will leads back to all methods being used to
gain access to those lists.

Having seen companies as large as AOL and Verio lose track of internal lists
of email address that then wound their way to Spammers, a better solution
relies on information that isn't damaging when public (i.e. SPF ns TXT
records).  Valid recipient bouncing is a short-term solution but like
greylisting, eventually ratware and tactics will catch up.

KAM