Re: [exim] listed at Backscatterer.org

On Fri, 2010-06-25 at 11:28 +0100, Ian Eiloart wrote:
> --On 24 June 2010 09:43:40 +0000 Kebba Foon <kebba.foon@???> wrote:
>
> >
> > Backscatterer - Why it is abusive and how to stop your system doing so
> >
> > Email servers should be configured to provide Non-Delivery Reports
> > (bounces) to local users only.
> > Unacceptable email from anywhere else should be rejected.
> >
>
> This is silly advice. It should be quite acceptable to bounce email that
> has an SPF pass, or that has a valid DKIM signature (provided the return
> path domain matches a signed From header domain). In both cases, if you're
> creating collateral spam, then that's the fault of the domain operator.
>
There is probably a bit of a translation issue there as backscatter.org
is part of Dirk & Claus 'UCEProtect' stable of blocklists.

My personal opinion is you should never accept mail that you cannot
deliver to a user and in such a scenario it should be rejected at SMTP
time - not after a 250 is given and (any/the) MTA decides it does not
want it for whatever reason. Exim is very flexible and its brilliant
ACL's can pretty much reduce backscatter to zero if configured
correctly.

I agree that if something passes an SPF check then a 'bounce' after a
250 should not be a serious issue, but again accepting stuff you can't
deliver is generally a bad plan.

With backscatter.org it is quite possible to get listed for doing
callouts (particular sender verification checks) and even
auto-responders if someone maliciously spoofs the mail from, and
spammers know it, so use them with care :-)