On 26 September 2007, Craig Skinner  wrote:

quoted text
> RW wrote:

> >

> > What I was getting looked like backscatter and smelled like backscatter

> > it is just that some of the IPs sending it didn't check out as MTAs.

> > i.e. they were not listed MXs for the domain they came from AND the

> > domain was not likely someone with separate outbound senders.

> >

> > They all retried too and when I had them as TRAPPED entries the logged

> > data included typical failed-to-deliver messages.

> >

>

> 'bots getting smart eh? Bugger! If that is the trend, greylisting starts

> to lose its value as spammers adapt to the RFCs.

[...]

    Greylisting is trivial to bypass, with or without a queue: just send

the same messages twice.  Some spammers have figured that out long ago.

Ever wondered why sometimes you receive 2 or 3 copies of the same spam,

from the same IP, with the same Message-Id etc., a few minutes apart?
    Regards,
    Liviu Daia
--

Dr. Liviu Daia                                  http://www.imar.ro/~daia