Does anyone know where I can find listings of what particular network belongs to what part of the world? We're getting slammed by spammers and I'm adding entire subnets to firewall lists however I don't want to squash legitimate email servers. For example I'm not sure if I've squashed servers that Gmail and Hotmail use as I've not seen test messages come in. I know what SMTP gateways they list for mail inbound to them however I don't believe they use the same servers for outbound email.