[CentOS] Trying to control the torrent of spam...

Wed Aug 31 20:25:06 UTC 2005
Kirk Bocek <t004 at kbocek.com>

> 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?"$&{client_addr}')dnl
	FEATURE(`dnsbl', `relays.ordb.org', `"Spam blocked see:
http://ordb.org/lookup/?host="$&{client_addr}')dnl
	FEATURE(`dnsbl', `cbl.abuseat.org', `"Spam blocked see:
http://cbl.abuseat.org/lookup.cgi?ip="$&{client_addr}')dnl
	FEATURE(`dnsbl', `sbl.spamhaus.org', `"Spam blocked see:
http://spamhaus.org/query/bl?ip="$&{client_addr}')dnl
	FEATURE(`dnsbl', `list.dsbl.org', `"Spam blocked see:
http://dsbl.org/listing?"$&{client_addr}')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