Scott Howard scott at
Sat Feb 20 05:28:41 UTC 2010

On Fri, Feb 19, 2010 at 5:20 PM, William Herrin <bill at> wrote:
> On Fri, Feb 19, 2010 at 3:30 PM, Rich Kulawiec <rsk at> wrote:
>> Barracuda's engineers apparently think
>> that using SPF stops backscatter -- and it most emphatically does not.
>> Reject gooooood, bounce baaaaaaad. [1]
> Whine all you want about backscatter but until you propose a
> comprehensive solution that's still reasonably compatible with RFC
> 2821's section 3.7 you're just talking trash.

In the case of Barracuda's long history of Backscatter the solution is
simple, and is implemented by most other mail vendors - it's called
"Don't accept incoming mail to an invalid recipient".

Barracudas used to have no way of doing address validation for
incoming mail, so they would accept it and then bounce it when the
next hop (eg, the Exchange server) rejected the recipient address.
They finally fixed this a few years ago, and can not integrate with
LDAP (and possibly others) for address validation. Of course, it's
still down to the admin to implement it...


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