[Mailman-Users] Block domain

[Dan Jones]

I want to block all mail from a specific domain.  Under Privacy
options/sender filters, in the box marked "List of non-member addresses
whose postings will be automatically discarded" I put ^domain.com.  This
should be a simple regular expression that will always match the domain
name, but I still get emails that a posts from whatever at domain.com needs
authorization, and I have to go in and delete it.  Why doesn't this
work, and what does work?