SMTP Error from my server?

[Chuck Swiger]

On Sep 17, 2007, at 4:05 PM, Chris Maness wrote:
>> Looks to me like a failed sender verification callout-- these are  
>> generally construed to be abusive.  I can't easily tell from your  
>> munging whether it's your server or Adelphia that's doing it, though.
>
> This is the only e-mail address that I am having this problem with,  
> and it has been going on for a year or so now.  What other info  
> would you guys need to tell what it is.  I guess I don't understand  
> the whole "sender verification callout"  I'll have to do a little  
> google to find out.

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.

-- 
-Chuck