[BBLISA] State of greylisting these days

[John Miller]

Our situation is interesting: our e-mail recipients are mostly students and
faculty.  For them, there's not so much concern about losing money, but we
do have students whose term papers didn't make it through, or faculty who
are concerned about grant applications.

The financial aspect of greylisting is worrisome, though: how many senders
are there out there who don't fully comply with greylisting, and have their
messages cast into oblivion?  In particular, I've seen sender MXes retry
every few seconds (annoying if they have a retry limit) or every 24 hours
(sorry-we don't keep greylist stats that long).

We too use milter-greylist, and it handles our 100k+ daily e-mails.  I'd
love to just turn it off--it's another layer of complexity in an already
complex process.  I can't just do so as a knee-jerk reaction, though: some
anecdotal evidence would be awesome.

(I may try scripting an smtp connection to a bunch of different
universities and see which do/don't greylist >:-) )

Does anyone use a greylist window ("wait at least a minute, no more than a
day") instead of a fixed time period?

John



On Thu, Jul 24, 2014 at 6:15 PM, Steven M Jones <bblisa-in at crash.com> wrote:

> On 07/24/2014 08:05 AM, John Miller wrote:
> >
> > Is anyone still using greylisting for their mail servers these days?
> > We're currently using milter-greylist with sendmail, and seems like
> > we're seeing more and more clients that don't handle it well--I'm
> > spending a couple of hours each week searching through mail logs,
> > whitelisting MXs, and letting everyone know what's happening.  Getting
> > kind of old; would like everyone's take on it.
>
> I've used milter-greylist for years on what amounts to a few personal
> domains, plus a dozen or so domains I'm MX for from that server. Made a
> big difference on introduction, but haven't turned it off to confirm
> current effectiveness. Usually it's nothing worse than an inconvenience
> for things like confirming account creation with various vendors and web
> forums. I very rarely have to add any new exceptions.
>
> Greylisting isn't something I recommend commercially because there are
> too many idiots in the world who think email is a combination of instant
> messaging and a file transfer protocol. A certain species of financial
> type likes to claim that "Millions Of Dollars!" are lost whenever their
> email messages take anything over 5 seconds, end-to-end. Sigh...
>
> --Steve.
>
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-- 
John Miller
Systems Engineer
Brandeis University
johnmill at brandeis.edu
(781) 736-4619
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