Problem

A Forum reader recently asked:

"I would like to know more about country level RBLs. Can you direct me to
any references?"

And here's the response from Michael Bell ...

Solution

You can block everything coming from a particular country by using Country-specific DNSBL Providers. These DNSBL providers list IP addresses of specific countries. The net-effect is that you can block e-mail session attempts per-country by using these DNSBL providers. This can be a very convenient and efficient way of blocking email from countries that you knowingly would never communicate with. A full description of this service can be found at:

www.countries.nerd.dk

The hostnames used for these DNS zones are based on the the International Organization for Standardization (ISO) geographical coding standard ISO 3166. The two letter coding standard as described in the ISO 3166-1 subset is used as the basis to identify these country-based DNSBLs.
Use these DNSBL providers at your own risk.