On Thu, 13 Nov 2014, listsb-spamassas...@bitrate.net wrote:
all of the emotional postulative opining aside, one possibility i have
been considering is having postfix delay relay of messages to the
content filter for a few minutes, as it seems that when these messages
reach us, they're only minutes away from being matched by network tests
[this is what i asked postfix-users about]. i'm interested to hear from
folks on this list regarding this idea, as well as possible alternatives
to dealing with this phenomenon.
It's called greylisting and many people (including myself) have good
results with it.
It is not, however, a panacaea.
if you're in a business environment you may have an uphill battle with
managing expectations, to wit: email is *not* intended to be instant
messaging - and may run up against the brick wall of management not being
willing to delay emails from prospective new paying clients *at all*. So
its attractiveness will depend on your userbase.
There are also historical problems with some MTAs that do not react
properly when told "go away for a few minutes". There are some that will
either never deliver the mail, or will incorrectly return it to the sender
as "undeliverable" rather than retrying after a delay. I think, though,
that the instance of broken mailers like that has gone way down over time.
Others may have more up-to-date information on that aspect, I've been out
of day-to-day monking for a decade now.
There are also misconfigured MTAs that *will* retry, but only at large
intervals (like 24 hours).
Known sites using problematic MTAs can be whitelisted, as can known
correspondents (e.g. regular clients).
The tools do exist and are mature and well-known, and doing this is
perfectly valid per the SMTP spec.
--
John Hardin KA7OHZ http://www.impsec.org/~jhardin/
jhar...@impsec.org FALaholic #11174 pgpk -a jhar...@impsec.org
key: 0xB8732E79 -- 2D8C 34F4 6411 F507 136C AF76 D822 E6E6 B873 2E79
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If you ask amateurs to act as front-line security personnel,
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