Beginning in late 2001, we started receiving vast amounts of junk e-mail (better known as spam) from Korean networks. Some of it was in Korean, a language that nobody here understands, some was in English. Despite repeated attempts to contact system managers to alert them to the problem, we never received even a single acknowledgement to any of our reports.
So, with regret, we have blocked mail from most South Korean networks.
The blocking mechanism is a DNSBL (DNS blocking list) called korea.services.net. It lists the numeric addresses of Korean networks, in a form that mail systems can check efficiently. See http://www.dnsbl.com/ for more info on DNSBLs.
DNSBLs are designed for software like sendmail, qmail, and postfix that handle mail transfers from one system to another. You can't easily use them from user programs like Eudora or Outlook. If you're not sure whether your mail system can use a DNSBL, it probably can't. Consult the people who run your mail system and see if they want to use it.
As far as I'm concerned, anyone is allowed to use it. Please be sure that your mail software is set up to use a local DNS server (BIND is the most common) rather than querying us directly, to limit the load. If the load becomes too large, we may ask heavy users to host mirror copies of the data. (If you don't understand these instructions, please consult the people who run your mail system, or the vendor that sold you your mail software.)
The database lists most IP address ranges assigned to Korea by APNIC, plus any older ARIN ranges with a history of sending spam. The list includes networks, not individual computers.
As networks clean up their act, get rid of their spammers, fix their abusable relays and proxies, and set up a reasonable procedure to receive and act on complaints, I have started removing well run networks from the list. My goal is to stop the flow of spam, not to cut anyone (other than spammers) off from the Net.
Note: The database includes networks, not individual computers. Do not write to ask to have your computer removed, unless your entire network has its spam problem under control.
For information about an address' entry in the list at korea.services.net, enter it as an IP address, four numbers separated by dots, and click Lookup.
Attention Postfix Users: Did you come here because korea.services.net appears to be blocking large amounts of non-Korean mail? Some widely distributed instructions for setting up DNSBLs in Postfix can be misleading. Be sure that this DNSBL is listed in a reject_rbl_client line in your configuration file.
Do not use a reject_rhsbl_client line. If you do Postfix will look up domain names, which it shouldn't, rather than IP addresses, which is what it should do.