Let me elaborate with an example: http://pastebin.com/AS6kvLH2
1.0 RCVD_IN_CSS RBL: Received via a relay in Spamhaus CSS
[64.120.212.26 listed in zen.spamhaus.org]
1.3 RCVD_IN_BL_SPAMCOP_NET RBL: Received via a relay in bl.spamcop.net
[Blocked - see
<http://www.spamcop.net/bl.shtml?64.120.212.26>]
1.3 RCVD_IN_RP_RNBL RBL: Relay in RNBL,
https://senderscore.org/blacklistlookup/
[64.120.212.26 listed in
bl.score.senderscore.com]
1.4 RCVD_IN_BRBL_LASTEXT RBL: RCVD_IN_BRBL_LASTEXT
[64.120.212.26 listed in
bb.barracudacentral.org]
1.7 URIBL_DBL_SPAM Contains an URL listed in the DBL blocklist
[URIs: universmallmail.com]
1.6 URIBL_WS_SURBL Contains an URL listed in the WS SURBL
blocklist
[URIs: universmallmail.com]
1.7 URIBL_BLACK Contains an URL listed in the URIBL
blacklist
[URIs: universmallmail.com]
3.5 BAYES_99 BODY: Bayes spam probability is 99 to 100%
[score: 0.9997]
0.0 RELAY_US Relayed through United States
1.7 RCVD_IN_HOSTKARMA_BL RBL: HostKarma: relay in black list
[64.120.212.26 listed in
hostkarma.junkemailfilter.com]
0.8 SPF_NEUTRAL SPF: sender does not match SPF record
(neutral)
0.1 SPF_HELO_NEUTRAL SPF: HELO does not match SPF record
(neutral)
0.0 HTML_MESSAGE BODY: HTML included in message
0.7 MIME_HTML_ONLY BODY: Message only has text/html MIME parts
0.1 KHOP_DNSBL_BUMP Hits a trusted non-overlapping DNSBL
0.4 MAY_BE_FORGED Relay IP's reverse DNS does not resolve to
IP
1.0 KHOP_DYNAMIC2 Relay looks like a dynamic address
seems wasted :)