Backscatter

PROBLEM: Mailman comes out of the box ready to backscatter spam people.

RESOLUTION:

1. Don't create backscatter aliases for subscribe/unsubscribe/etc by default. Nearly everyone uses web based signup.
2. Discard or hold messages from non-subscribers by default. 

DETAILS:

Removing aliases depends on the installation method.

• If using mm-handler, an experimental version is available that can optionally remove support for the problem aliases at http://home.uchicago.edu/~dgc/sw/mailman/mm-handler/mm-handler-2.10.

To change the way messages from non-subscribers are handled, edit /etc/mailman/sitelist.cfg and change the value of the setting generic_nonmember_action to 1 (Hold) or 3 (Discard).