Today I went through the “Finally blocking some spam” titled conversation on the postfix mailing list. While I do not like the main idea of this discussion at all, e.g. blocking SMTP connections on the firewall level by whole IP country blocks, there are several interesting links:
- invaluement DNS BL
Another BL which claims to blocking 40% of connections *after* zen and spamcop. Though, costs money.
- The South Korean Network Blocking List
- Greylisting: The Next Step in the Spam Control War
Evan Harris is an enthusiastic GrayListing fan (as I am too). This page is devoted to promote and to explain GrayListing.
- Unlisting – Port Knocking for SMTP
Unlisting is another technique to fight SPAM.
- Nolisting – Poor Man’s Greylisting
And another greylisting option.
- Country IP Blocks: Network Allocations by Country with Searchable IP Database
Nice … I suspect this is something like GeoIP but free – and updated every 2 hours.
- policyd-weight – A policy daemon for Postfix
- UCEPROTECT®-Network Project
Another anti SPAM solution again