[CLUE-Tech] reverse DNS

[Charles Oriez]

At 08:33 PM 9/11/2004, you wrote:

>Charles Oriez wrote:
>[...]
>>as an anti-spam tool, rejecting traffic from servers without valid RDNS 
>>rejects a significant percentage of spam.  spam sent through trojaned
>>machines in particular tend not to have valid rdns
>
>Do you have false positive and false negative numbers for that 
>technique?  Preferrably independent of other filters.
>
>Do you reject (based on RDNS) at SMTP time or after?
>
>Dave

Sendmail has a feature for reject for invalid RDNS.

http://www.sendmail.org/m4/features.html

As to false positives, we have yet to have a report from anyone that a mail 
bounced that shouldn't have.





--

Charles Oriez     coriez at oriez.org    39  34' 34.4"N / 105 00' 06.3"W
**
"Drag God into politics, and you'll ruin his reputation in no time." -
Molly Ivins