Re: Intel.com Mailing List Arbitrary Address Removal Link

[Joel Maslak <jmaslak () antelope net>]

On Tue, 5 Feb 2002, E M wrote:

> .: Problem :.
> While Intel requires you to login to modify account information, it does not
> require you to login to remove your e-mail (or any e-mail) from its mailing
> list database.

This is nothing new.

The web interface is new, but being able to remove users from mailing
lists without any verification is not.

Many mailing lists - especially large volume ones - will remove any
address that bounces.  Creating a forged bounce request is quite trivial.

The fix for this requires sophisticated bounce tracking software.  The
only real way to fix this problem is to send each recipient a message with
a custom-encoded FROM envelope address, such as:
        bounce-<user-id>-<security-key>@example.com
Where the user-id is some sort of database identifyer and the security key
is simply a random number kept in the database to prevent malicious
activity (it could also be some sort of cryptographic code).  When the
example.com mail server receives a message to bounce-xxx-yyy () example com,
it checks the security key, verifies that the bounce is a permanent
bounce, and deletes the user.

You can also do something similar with WWW removal links:
        Click http://remove.example.com/<user-id>/<security-key>

Most mass mailing systems don't do any of this, though, since this
requires sending a unique message to every recipient.  Instead of sending
one body with lots of envelope addresses to, say, AOL, you end up sending
lots of complete messages - including duplicate copies of the body - to
AOL.

-- 
Joel Maslak