Re: [exim] sender verify and greylisting

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Auteur: David Woodhouse
Datum:  
Aan: W B Hacker
CC: exim users
Onderwerp: Re: [exim] sender verify and greylisting
On Fri, 2006-07-14 at 08:02 +0800, W B Hacker wrote:
> > mail from: <>
> > 250 Ok
> > rcpt to: test@???
> > 450 <test@???>: Recipient address rejected: Greylisted for 300
> > seconds (see http://...)
> >
>
> The above is only one of many false-positives.


'many'?

Poor greylisting implementations (at RCPT instead of DATA time) do
interact badly with sender verification callouts sometimes -- but the
message should get through after it's retried. When they attempt to
resend the message from test@???, once the 300 seconds has
elapsed, it should get through.

> The Exim MLM on sesame, for example fails sender verify at 'recipient', yet is
> certainly on MY list of 'good guys'.


What address? exim-users@???? That fails sender verification
because it's never used as an SMTP reverse-path in valid mail. It's the
same with the address 'dwmw2@???'. In both cases, sender
verification does exactly the right thing.

Using sender verification as an all-or-nothing test, and either
rejecting or deferring (as in the above-quoted example) is something
that works well for many people.

The only time it breaks is when people are sending you messages that you
can't send bounces for -- which means you're likely not to be able to
reply either. So they'll _think_ that they managed to communicate, but
in fact you can't get back to them. It's better, in most of those cases,
for the mail never to leave their own system. That way they know they've
broken it.

Btw, your MUA is misbehaving -- your replies have neither In-Reply-To:
nor References: headers, so they're not associated with the thread to
which you replied. Please could you fix that so that you don't break the
threading on the list?

--
dwmw2