Hi List

Well thank you for all the hints. I also (thanks to Al) found out, that
you need to set the browser language to english, to get to the propper
help page where the delisting request form can be found. With german,
you're lost :-)

But I would like to use that topic on a discussion about what to do to
mitigate abuse of an ISP email platform.

I believe we do much to mitigate abuse from our email platform, but
perhaps, there is more that can be done. So tell me how you 'do' it and
where you see potential for improvement.

First let me explain what we do...

We are a classical end user ISP. Our customers are private households
with an internet connection and some companies. We encourage companies
to use an own mailserver. We do not offer any 'relay' services to them,
so we won't get the crap some hacked company servers produce via our
mail platform (of course our abuse desk also deals with them, to
notify those customers in our AS).

So we mainly get the usual problems with customers who hand out their
email credentials in reply to phishing emails or get trojans who steal
them from their computers.

To mitigate those problems we have implemented those mechanisms:

* Require minimal password strength.
* Require SMTP Authentication.
* Keep cache history from which IP an SMTP Authentication occurred.
* If count(IP) in delta time > IPlimit block account and require
  password change.
* If count(geoIP) in delta time > Geolimit block account and require
  password change.

Some exception for google services and local mobile networks NAT which
use a different ip for each SMTP connections.

* If count(recipients) in delta time > RecipientLimit - tempfail and
  notify postmaster to check manually.

We also use account encapsulated SRS for forwarded emails, so we can
detect bounces from the far side and deactivate bouncing forwards to
limit backscatter to a minimum.

Of course, this fails if the phished account keeps below our radar by
using a single ip address and sending emails slowly to keep below the
tempfail threshold.

In this case we rely on feedback loops to 'react' and also sometimes on
customers reporting the bounces their phished account produces as
spam :-)

What else could we do?

Mit freundlichen Grüssen

-Benoît Panizzon-
-- 
I m p r o W a r e   A G    -    Leiter Commerce Kunden
______________________________________________________

Zurlindenstrasse 29             Tel  +41 61 826 93 00
CH-4133 Pratteln                Fax  +41 61 826 93 01
Schweiz                         Web  http://www.imp.ch
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