Edited my /opt/zimbra/conf/spamassassin/local.cf to look like this (according to article regarding improving antispam solution):

As I understand, razor2 etc is installed now by default, so all I have done basicly is to install red hat enterprise linux 5, fetchmail, disbaled exim, installed gmp as required during the install and then edited the local.cf according to below paste, am I good to go or is there other things I should consider? Also is SPF enabled now by default?

# This is the right place to customize your installation of SpamAssassin.
#
# See 'perldoc Mail::SpamAssassin::Conf' for details of what can be
# tweaked.
#
# Only a small subset of options are listed below
#
################################################## #########################

# Add *****SPAM***** to the Subject header of spam e-mails
#
# rewrite_header Subject *****SPAM*****


# Save spam messages as a message/rfc822 MIME attachment instead of
# modifying the original message (0: off, 2: use text/plain instead)
#
# report_safe 1


# Set which networks or hosts are considered 'trusted' by your mail
# server (i.e. not spammers)
#
# trusted_networks 212.17.35.


# Set file-locking method (flock is not safe over NFS, but is faster)
#
lock_method flock


# Set the threshold at which a message is considered spam (default: 5.0)
#
# required_score 5.0


# Use Bayesian classifier (default: 1)
#
# use_bayes 1


# Bayesian classifier auto-learning (default: 1)
#
# bayes_auto_learn 1


# Set headers which may provide inappropriate cues to the Bayesian
# classifier
#
# bayes_ignore_header X-Bogosity
# bayes_ignore_header X-Spam-Flag
# bayes_ignore_header X-Spam-Status

score SPF_FAIL 10.000
score SPF_HELO_FAIL 10.000
score RAZOR2_CHECK 2.500
score PYZOR_CHECK 2.500
score BAYES_99 4.300
score BAYES_90 3.500
score BAYES_80 3.000

# Score to reduce the effect of Bonded Sender Program (BSP) whitelisting
score RCVD_IN_BSP_TRUSTED -0.500
score RCVD_IN_BSP_OTHER -0.500
score RCVD_IN_BONDEDSENDER -0.500

# Score to reduce the effect of Habeas whitelisting
score HABEAS_ACCREDITED_COI 0 -0.5 0 -0.5
score HABEAS_ACCREDITED_SOI 0 -0.25 0 -0.25
score HABEAS_CHECKED 0 -0.1 0 -0.1

# Score to reduce the effect of ISIPP/IADB SuretyMail whitelisting
score RCVD_IN_IADB_VOUCHED 0 -0.2 0 -0.2
score RCVD_IN_IADB_DOPTIN 0 -0.4 0 -0.4
score RCVD_IN_IADB_ML_DOPTIN 0 -0.6 0 -0.6