dnsbl-milter - Sendmail DNSBL & DNSWL milter. Simple anti-spam solution for e-mail service providers

Features

supports SMTP authentication - that is, users can bypass the blacklist listing by authenticating via SMTP AUTH
supports sender address verification or sender callbacks (see milter-sender) - most SMTP callbacks are made using the null-envelope sender address. When we see this, we defer our blacklist checks until the SMTP DATA stage (or xxfi_data() callback in Sendmail 8.14.0+'s milter API)
customizable blacklists (defaults are SpamCop and Spamhaus) and whitelists (default is to use DNSWL.org) - we chose these blacklists and whitelists due to various documents online comparing some of the popular blacklists. See links provided in the "Links" section
. . . and more. . .

So why choose dnsbl-milter over Sendmail's builtin dnsbl/enhdnsbl feature?

allows use of DNS whitelists to override DNS blacklist listings
allows more control as to what IPs/ports (daemon_options) we want DNSBL filtering
relay lines does not override listing (See 510 Software Group's explanation)
. . . and more to come

1.0 (for Sendmail 8.14.0+)
1.0 (pre Sendmail 8.14.0)

Other releases

check source, make sure DNSBLs and DNSWLs are the ones you want. By default, we're using SpamCop, Spamhaus and DNSWL.org
compile source

# make
install compiled program

# make install
add something like the line below to sendmail.mc file:

INPUT_MAIL_FILTER(`dnsbl-milter', `S=unix:/var/run/milter/dnsbl-milter.sock, T=C:5m;S:20s;R:5m;E:10m, F=T')dnl
add "dnsbl-milter" to the "InputMailFilters" parameter in DAEMON_OPTIONS
generate new sendmail.cf file from sendmail.mc
run dnsbl-milter manually or use the init.d script provided in the source repository.

# /usr/local/sbin/dnsbl-milter --user milter --group milter --bind unix:/var/run/milter/dnsbl-milter.sock --daemon

That's it. Watch the logs and watch your spam drop.

http://sourceforge.net/projects/dnsbl-milter
Report bugs, post patches, request new features, get support. . .