[Greylist-users] Tempfail before or after DATA section? (was Re: Greylisting via Exim 4 local_scan harmful?)

[Tim Freeman]

I took Bill's advice and configured my mailer to send the tempfail's
before the DATA section instead of after.

However, the comment in relaydelay.conf before the configuration
variable says there are mailers who get it wrong the opposite way from
the one Bill observed.  Bill's example has more details and is more
recent than the one listed below, and on the balance even Evan Harris,
the relaydelay author, says that doing it after the DATA is "generally
discouraged" according to the comment below.  

Thus, as far as I can tell, there seems to be a consensus that the
tempfail should be done before the DATA section.

# Set this to a nonzero value if you want to wait until after the DATA
#   phase before issuing the TEMPFAIL for delayed messages.  If this
#   is undefined or zero, then messages will be failed after the RCPT
#   phase in the smtp session.  Setting this will cause more traffic,
#   which should be unneccessary, but increases the fault tolerance for
#   some braindead mailers that don't check the status codes except at
#   the end of a message transaction.  It does expose a couple of 
#   liabilities, in that the blocking will only occur if the LAST recipient
#   in a multi-recipient message is currently blocked.  If the last
#   recipient is not blocked, the message will go through, even if some
#   recipients are supposed to be blocked.  Generally discouraged.

-- 
Tim Freeman                                                  tim at fungible.com
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