I've got a server at home running postfix which is nice and secure. All the domains it receives email for are registered with Just The Name and so incoming email comes through the Metronet/Plusnet servers and I've got my plusnet email set up to do SMTP forwarding. I have one domain which isn't through JTN and I've not actually got MX records set up for it but I'm seeing a huge amount of spam being attempted to be delivered to this domain. It is all email to non-existent users so its rejecting the attempts to deliver it. I'd like to be able to restrict my server so only authenticated sessions (which I've got working) and the Metronet/plusnet servers can actually connect to the server to attempt delivery. The obvious way would be to add the plusnet/metronet email servers to the my_networks list. Has anyone tried this and if so what addesses do I need to put into the my_networks list to get it to work?