Milter-greylist

> From: milter-greylist@yahoogroups.com On Behalf Of Dan Mahoney, System
Admin
> 
> All,
> 
> I just spent an hour trying to explain greylisting to one of my end-users

  Been there, done that. :)  When the smoke cleared I ended up creating a
daily
report that users could opt into that would tell them what had been filtered
from
their mailbox during the previous 24 hours, and why.  The explination for
greylisting went something like this:

  Any mail server attempting to send you email, that cares whether you
actually
receive that email, will attempt to deliver it more than once.  This is
because
there are a large number of reasons why the first attempt might not succeed,
the
Internet is far from a perfect system.  Greylisting is where we reject the
first
attempt at delivering the message to you, knowing that they will try again a
little later.  This works because spammers using hijacked PC's don't retry
delivery while properly configured mail servers do.

  However, there are always mail servers run by companies who you'd think
should
know what they are doing, that are actually run by idiots, or even
deliberatly
configured to throw away the email to you if it can't be delivered the first
time
they try.  You'd be surprised at the names of some of these companies, we
were
the first time we saw it happen.  So, if you really care to receive email
from
companies that have made it clear they don't care whether email they send to
you actually gets to you, you may check the following box to disable
Greylisting
on your account.

  [ ] Disable greylisting on my email account.

  Warning: this will potentially expose your email account to a significant
increase in spam.  By reading your daily filtering report for a week or so,
and watching how much filtering is done by Greylisting, you will be better
equiped to understand the risk.

  All this was done via a daily email to the user, if they'd actually had
any
email filtered, and it directed them to an internal website where they could
access a filtering control form that contained the above text and checkbox.
Users who called the support desk and asked "could you just let this one
email
through" were told to access the webpage and disable Greylisting in general,
or we'd disable it for them if they didn't want to use the form.  After a
few
months of use we found that most customers quickly turned greylisting back
on
once they saw what they'd have to wade through.  We also encouraged them to
write to the sender who's email didn't get delivered because of a defective
or mis-configured mail server and have them bitch at their ISP and demand to
know why their outgoing email wasn't being sent with proper retries.