I have customized alot of my rules, but I will post what I have here.
# SpamAssassin user preferences file. See 'perldoc Mail::SpamAssassin::Conf'
# for details of what can be tweaked.
###########################################################################
# How many hits before a mail is considered spam.
# required_hits 10
# Whitelist and blacklist addresses are now file-glob-style patterns, so
# "friend@somewhere.com", "*@isp.com", or "*.domain.net" will all work.
# whitelist_from someone@somewhere.com
# Add your own customised scores for some tests below. The default scores are
# read from the installed spamassassin rules files, but you can override them
# here. To see the list of tests and their default scores, go to
#
http://spamassassin.org/tests.html .
#
# score SYMBOLIC_TEST_NAME n.nn
# Speakers of Asian languages, like Chinese, Japanese and Korean, will almost
# definitely want to uncomment the following lines. They will switch off some
# rules that detect 8-bit characters, which commonly trigger on mails using CJK
# character sets, or that assume a western-style charset is in use.
#
# score HEADER_8BITS 0
# score HTML_COMMENT_8BITS 0
# score SUBJ_FULL_OF_8BITS 0
score REMOVE_IN_QUOTES 4
score CLICK_TO_REMOVE_2 3
score TRACKER_ID 6
score LINES_OF_YELLING 3
score LINES_OF_YELLING_2 5
score LINES_OF_YELLING_3 7
score BLANK_LINES_70_80 3
score BLANK_LINES_80_90 4
score BLANK_LINES_90_100 4.5
score NO_REAL_NAME 3
score FROM_ENDS_IN_NUMS 4
score FROM_STARTS_WITH_NUMS 4
score FROM_HAS_MIXED_NUMS2 4
score FROM_OFFERS 4
score TO_EMPTY 7
score UNDISC_RECIPS 3
score FAKED_UNDISC_RECIPS 4.5
score PLING_QUERY 5
score SUBJ_HAS_UNIQ_ID 4
score SUBJ_HAS_SPACES 7
score score SUBJ_ALL_CAPS 3
score ADVERT_CODE 3
score ADVERT_CODE2 3
score LOTS_OF_CC_LINES 4
score FORGED_AOL_RCVD 4
score FORGED_HOTMAIL_RCVD 4
score FORGED_HOTMAIL_RCVD2 4
score FORGED_YAHOO_RCVD 4
score X_PRIORITY_HIGH 7
score X_MSMAIL_PRIORITY_HIGH 7
score USER_IN_BLACKLIST 100
score USER_IN_WHITELIST -1000
score SUBJ_AS_SEEN 4
score SUBJ_DOLLARS 6
score SUBJ_DOUBLE_YOUR 6
score SUBJ_FOR_ONLY 6
score SUBJ_FREE_CAP 6
score SUBJ_FREE_INSTANT 4
score SUB_FREE_OFFER 4
score SUBJ_GUARANTEED 6
score SUBJ_LIFE_INSURANCE 4
score SUBJ_NOW_ONLY 6
score SUBJ_RIPPED 10
score SUBJ_VIAGRA 10
score SUBJ_YOUR_DEBT 10
score USERNAME_IN_SUBJECT 7
score LOSE_POUNDS 10
score SAVINGS 5
score HTML_00_10 0.5
score HTML_10_20 1.0
score HTML_20_30 1.5
score HTML_30_40 2.0
score HTML_40_50 2.5
score HTML_50_60 3.0
score HTML_60_70 3.5
score HTML_70_80 4.0
score HTML_80_90 4.5
score HTML_90_100 5.0
score REMOVE_SUBJ 2
score SUBJ_REMOVE 2
score REPLY_REMOVE_SUBJECT 2
score DISCONTINUE 2
score REMOVE_FROM_LIST 2
score REMOVE_REMOVAL_1WORD 2
score REMOVE_REMOVAL_2WORD 2
score CLICK_TO_REMOVE_1 2
score HTML_FONTCOLOR_GRAY 5
score HTML_FONTCOLOR_RED 5
score HTML_FONTCOLOR_YELLOW 5
score HTML_FONTCOLOR_GREEN 5
score HTML_FONTCOLOR_CYAN 5
score HTML_FONTCOLOR_BLUE 5
score HTML_FONTCOLOR_MAGENTA 5
score HTML_FONTCOLOR_UNKNOWN 5
score BULK_EMAIL 10
score DIRECT_EMAIL 10
score MASS_EMAIL 10
score EMAIL_MARKETING 10
score VIAGRA 10
score NATURAL_VIAGRA 10
score HERBAL_VIAGRA 10
score TARGETED 7
score PENIS_ENLARGE 10
score PENIS_ENLARGE2 10
score IMPOTENCE 10
score MARKET_SOLUTION 10
score DIET 10
score RCVD_IN_BNBL 7
score LOSEWEIGHT 10
score LOSEBODYFAT 10
score RAVAGESOFAGING 10
score GENERIC_VIAGRA 10
score LARGE_COLLECTION 5
score FREE_PORN 10
score BARELY_LEGAL 10
score MEGA_SITE 10
score CUM_SHOT 10
score ALL_CAP_PORN 10
score PAY_SITE 10
score SEX_FEST 10
score LIVE_PORN 10
score HARDCORE_PORN 10
score HOT_NASTY 10
score BEST_PORN 10
score NASTY_GIRLS 10
score AMATEUR_PORN 10
score CELEBRITY_PORN 10
score ADULT_SITE 10
score RAPE 10
score PORN_PASSWORD 10
score PORN_6 10
score PORN_MEMBERSHIP 10
score PORN_GALLERIES 10
score PORN_15 10
score PORN_16 10
score DISGUISE_PORN 10
score WWW_CLIK4YOU_COM 4
score UNSUB_SCRIPT 3
score UNSUB_PAGE 3
score REMOVE_PAGE 3
score BTAMAIL_URL 4
score CHINA_URL 4
score BAYES_00 0.5
score BAYES_01 1
score BAYES_10 1.5
score BAYES_20 2.0
score BAYES_30 2.5
score BAYES_40 3.0
score BAYES_44 3.5
score BAYES_50 4.0
score BAYES_56 4.5
score BAYES_60 5.0
score BAYES_70 5.5
score BAYES_80 6.0
score BAYES_90 6.5
score BAYES_99 7.0
required_hits 10
rewrite_subject 1
subject_tag *****SPAM*****
# WHITELIST
whitelist_from *@anynall.com
whitelist_from *@thejokes.net
whitelist_from *internet.com
whitelist_from PCM_Insider@eletters.pcmag.com
whitelist_from PCM_Tips@eletters.pcmag.com
whitelist_from emailspecial@cyclesportmag.com
whitelist_from offers@testprep.selftestsoftware.com
whitelist_from weather@inbox.weather.com
whitelist_from *@ebay.com
# BLACKLIST
# blacklist_from *@*.*
I have mine configured for very specific instances, the kind and type of spam that I receive. Alot you can probably use as well. I do not delete the messages, but I have set up a rule in Outlook Express to automatically move any message that contains "*****SPAM*****" in the subject to a SPAM folder. SpamAssassin has roughly marked about 2,500 messages as spam since I enabled it, about 6 months ago.
My customizations are small compared to the list of tests that SA has on their website (