On Sun, 2005-08-28 at 11:01, Preston Crawford wrote: If you were running your own MTA I would recommend you implement greylisting. This would eliminate >98% of spam with little or nor impact to your MTA servers resources.

On my CentOS 3.5 sendmail server I simply added:

FEATURE(`blacklist_recipients')dnl dnl # dnl # dnsbl - DNS based Blackhole List/Black List/Rejection list dnl # See http://www.sendmail.org/m4/features.html#dnsbl dnl # FEATURE(`dnsbl', `bl.spamcop.net', `"Spam blocked see: http://spamcop.net/bl.shtml?%22$&%7Bclient_addr%7D%27)dnl FEATURE(`dnsbl', `relays.ordb.org', `"Spam blocked see: http://ordb.org/lookup/?host=%22$&%7Bclient_addr%7D%27)dnl FEATURE(`dnsbl', `cbl.abuseat.org', `"Spam blocked see: http://cbl.abuseat.org/lookup.cgi?ip=%22$&%7Bclient_addr%7D%27)dnl FEATURE(`dnsbl', `sbl.spamhaus.org', `"Spam blocked see: http://spamhaus.org/query/bl?ip=%22$&%7Bclient_addr%7D%27)dnl FEATURE(`dnsbl', `list.dsbl.org', `"Spam blocked see: http://dsbl.org/listing?%22$&%7Bclient_addr%7D%27)dnl

to my sendmail.mc file. I'm sure it will work in CentOS 4. I forget where I found the instructions for blacklisting. This has dramatically reduced the spam on my server.

Kirk Bocek