1&1 (1und1.com, 1and1.com) Censors Internet Traffic

1&1, the web and server hoster in Germany has silently started
to filter and block all IP packets coming from IPs that are
listed in some RBL/DNSBL Spam databases like zen.spamhaus.org .
1&1 blocks the traffic on their border routers.
The customers, especially server operators, have not been informed
nor asked whether they want filtered or unfiltered IP traffic.
There is no choice at 1&1.