The IMRSS open-mail-relay-protection service has listed one of my machines, 129.173.1.10, as an open mail relay, I dunno why, coz it ain't. Several regular mail peers have called me about this.

Most likely it's listed because it relays for other, open hosts.

Is anyone running this thing? or is it an unattended dinosaur causing more problems than it solves?

Well, IMRSS also lists the following: 129.173.1.56 129.173.1.67 129.173.1.83 129.173.1.88 which *are* indeed open relays. So even if 129.173.1.10 is closed, you still have several other open relays on your network. Steinar Haug, Nethelp consulting, sthaug@nethelp.no