I've just found a new and interesting spam source - legitimate bounce messages

[eculp at casasponti.net]

Jeremy Chadwick <koitsu at FreeBSD.org> escribió:

> On Thu, Oct 16, 2008 at 05:38:07PM +0100, RW wrote:
>> On Thu, 16 Oct 2008 08:54:55 -0700 (PDT)
>> Luke Dean <LukeD at pobox.com> wrote:
>>
>> >
>> >
>> > On Thu, 16 Oct 2008, Matthew Seaman wrote:
>> >
>> > > Until the wonderful day that the entire internet abides by these
>> > > rules[*], use
>> > > of technologies like SPF and DKIM can discourage but not entirely
>> > > prevent the spammers from joe-jobbing you.
>> >
>> > I just started getting these bouncebacks en masse this week.
>> > My mail provider publishes SPF records.
>>
>> SPF increases the probability of spam being rejected at the smtp
>> level at MX servers, so my expectation would be that it would exacerbate
>> backscatter not improve it.
>
> Just a side comment for added clarity: this ultimately depends on how
> the mail server administrator implemented SPF.  For example, our mail
> servers *do not* do SPF lookups at the SMTP level (e.g. in postfix)
> because 1) the added complexity is not worth it, and 2) spammers are
> now hijacking DNS.
>
> Instead, our servers use SPF in SpamAssassin, subtracting from
> the spam probability score if an SPF record is found and matches
> appropriately.

That sounds like it is definitely worth trying.

Thanks,

ed
>
> --
> | Jeremy Chadwick                                jdc at parodius.com |
> | Parodius Networking                       http://www.parodius.com/ |
> | UNIX Systems Administrator                  Mountain View, CA, USA |
> | Making life hard for others since 1977.              PGP: 4BD6C0CB |
>
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