SMTP Error from my server?

[Jay Chandler]

Chuck Swiger wrote:
>
> The idea is pretty simple: when someone sends you an email, you delay 
> accepting it until you can confirm that you can send a reply back to 
> the sending address, or more precisely, check whether you can do a 
> MAIL FROM: your domain and RCPT TO: the sender, and have it return OK, 
> without actually going into the DATA phase and delivering a test message.
>
> This idea works fine for normal email addresses, but fails miserably 
> with certain types of automated email which is not intended for people 
> to reply to, and it also tends to lose out with TDMA 
> (http://tmda.net/).  More importantly, it also fails to work with 
> itself-- other people using "sender verification callouts" cause a 
> loop of failed deliveries, as neither side trusts the other.
>
The larger problem as well is that it doesn't scale.  Someone forging a
 From header out of a botnet could easily DDoS a smaller server
completely off the net if enough people implemented this system.

Antispam measures that are in and of themselves abusive aren't generally
considered to be good ideas.

-- 
Jay Chandler / KB1JWQ
Living Legend / Systems Exorcist
Today's Excuse: SCSI Chain overterminated