Re: emails to non existent recipients -- netzero.com fixed this problem?

[SM <sm...@resistor.net>]

At 02:57 13-06-2007, Mike Kenny wrote:
>On a related topic, <http://netzero.com>netzero.com has been 
>refusing connections from our SMTP servers. When I queried them the 
>response I got was:
>
>have been blocked because we detected probe attempts. Activities 
>like sending mail to non-existent accounts or empty connections 
>would qualify as a "dictionary search" or "probing for valid 
>addresses" and IP's used for such activity would be automatically 
>blocked for a temporary period.

Were you sending mail to non-existent accounts or doing sender validation?

>Subsequent communications have dealt only with the non-existent 
>accounts. Does blocking us on this basis make any sense? And has 
>anybody else encountered similar issues with netzero? If so, how resolved?

Yes, it does if most of the connections are for non-existent 
accounts.  It can be resolved by not doing that.

Regards,
-sm 

Re: emails to non existent recipients -- netzero.com fixed this problem?

[SM <sm...@resistor.net>]

Hi Mike,
At 08:50 13-06-2007, Mike Kenny wrote:
>we weren't sending anything. We are an ISP providing email services 
>to a large number of users in  South Africa. Some of these users may have:
>
>mis-remembered an email
>mis-typed an email
>sent to an acquaintance who had changed email provide (maybe because 
>they weren't receiving their emails :-)
>responded to a forged spam

The above should not cause a block unless you don't send a lot of 
"valid" mail to the provider.

>been abusing our system

As you are an ISP and you are servicing an area which has a lot of 
lawyers, the amount of abuse can be significant.  I assume that you 
have taken measures to detect and keep that type of email to a minimum.

>but the possibilities cover a lot of ground. I have had a further 
>communication from netzero asking that I check for email addresses 
>that look unlikely. I am doing this, but apart from the fact that 
>many of the large ISPs provide emails that look unlikely due to the 
>appending of digits, we have over 10 official languages here and an 
>address that looks unlikely in English may make perfect sense in 
>Zulu or Xhosa.

It's difficult to check for email addresses that look unlikely.  As 
you said above, people may read the local-part of the email address 
differently if they are using a language which is not 
English.  Consecutive digits may look like a dictionary attack and 
trigger alerts at the receiver's end.  A traffic analysis should give 
you a better picture of what's going on.

Regards,
-sm 

Re: emails to non existent recipients -- netzero.com fixed this problem?

[Mike Kenny <in...@gmail.com>]

On 6/13/07, SM <sm...@resistor.net> wrote:
>
> Were you sending mail to non-existent accounts or doing sender validation?



we weren't sending anything. We are an ISP providing email services to a
large number of users in  South Africa. Some of these users may have:

mis-remembered an email
mis-typed an email
sent to an acquaintance who had changed email provide (maybe because they
weren't receiving their emails :-)
responded to a forged spam
been abusing our system

but the possibilities cover a lot of ground. I have had a further
communication from netzero asking that I check for email addresses that look
unlikely. I am doing this, but apart from the fact that many of the large
ISPs provide emails that look unlikely due to the appending of digits, we
have over 10 official languages here and an address that looks unlikely in
English may make perfect sense in Zulu or Xhosa.

>Subsequent communications have dealt only with the non-existent
> >accounts. Does blocking us on this basis make any sense? And has
> >anybody else encountered similar issues with netzero? If so, how
> resolved?
>
> Yes, it does if most of the connections are for non-existent
> accounts.  It can be resolved by not doing that.



As I said above we don't do that.

Regards,
> -sm



Thanks for showing the interest anyway

Mike