sendmail: open-relay

[Peter Ulrich Kruppa]

Hi,

I am running my own small mail-server, i.e. I use my desktop pc for
sending and receiving my private mails.
That worked quite nicely the last years. From time to time I tested my
mail-server via abuse.net's mail-relay tester. - Never got any
positives.
Now suddenly I receive one:
        This is a test of third-party mail relay, generated via the
        Network Abuse Clearinghouse at http://www.abuse.net.
        
            Target host = 213.146.114.24 pukruppa.net
            Test performed by <ulrich at pukruppa.net> from 213.146.114.24
        
        A well-configured mail server should NOT relay third-party
        email.
        Otherwise, the server is subject to abuse by vandals and
        spammers,
        and probable blacklisting by recipients of the unwanted
        third-party
        e-mail.
Of course I had some fun trying to read sendmail's documentation. But I
guess I need some help with this.

I am running FreeBSD -STABLE 8.0 amd64 .
I don't think I ever played around with sendmail's configuration. I just
use it as came out of the box.

Any ideas?

Uli.