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

[RW]

On Thu, 16 Oct 2008 11:58:44 -0500
eculp at casasponti.net wrote:

> RW <fbsd06 at mlists.homeunix.com> escribi__:
>
> > Many people recommend SPF for backscatter, but I've yet to hear a
> > cogent argument for why it helps beyond the very optimistic hope
> > that spammers will check that their spam is spf compliant.
> 
> I feel the same way and thanks for adding some humor to the situation.

Actually that wasn't a joke, some people do cite that as the reason
why SPF helps with backscatter, that spammers will leave your domain
out of the "mail from" line if you publish SPF records for it.