Administration Control Panel -> Users and Groups -> Custom profile fields
[Create new field]: antibot (Field identification: antibot, Field type: Numbers)
Display in user control panel: Yes
Display on registration screen: Yes
Required field: Yes
Field name: Anti-Bot check
Field description: 如果您不是机器人，请输入一个130到139之间的数字:
[Profile type specific options]
Lowest allowed number: 130
Highest allowed number: 139
没有用mod，目前为止好像有效，是俺搞完后做的记录，看不明白的可以问，

还有一个办法是使用初始发帖审核，可阻止垃圾帖泛滥，但不能应对注册，设置很简单：
Administration Control Panel -> General -> Post settings
Enable queued posts: Yes
默认的最大帖子数是3，也就是说，只有前3帖通过审核发表后，用户才能自由发帖。
否则你发了他也不显示。。。
注意这个是3.0.0以后版本才有的功能（3.0.0本身木有）

下面是/etc/amavis/conf.d/20-debian_defaults文件中的部分：

$sa_spam_subject_tag = ‘***SPAM*** ‘;
$sa_tag_level_deflt = 2.0; # add spam info headers if at, or above that level
$sa_tag2_level_deflt = 6.31; # add ‘spam detected’ headers at that level
$sa_kill_level_deflt = 6.31; # triggers spam evasive actions
$sa_dsn_cutoff_level = 10; # spam level beyond which a DSN is not sent

应该寻找一种办法，可以指定whitelist，现在指定whitelist好像不起作用。

===========
修改了/etc/spamassassin/nano local.cf文件，加入了：
whitelist_from *@lzb.ac.cn
还修改了/var/lib/amavis/.spamassassin/user_prefs文件，进行了同样的修改，不知道那个起作用。
这个文件内容如下：

# SpamAssassin config file for version 2.5x
# generated by http://www.yrex.com/spam/spamconfig.php (version 1.01)

# How many hits before a message is considered spam.
required_hits 5.0

# Whether to change the subject of suspected spam
rewrite_subject 1

# Text to prepend to subject if rewrite_subject is used
subject_tag *****SPAM*****

# Encapsulate spam in an attachment
report_safe 1

# Use terse version of the spam report
use_terse_report 0

# Enable the Bayes system
use_bayes 1

# Enable Bayes auto-learning
auto_learn 1

# Enable or disable network checks
skip_rbl_checks 0
use_razor2 1
use_dcc 1
use_pyzor 1

# Mail using languages used in these country codes will not be marked
# as being possibly spam in a foreign language.
# – chinese english
ok_languages zh en

# Mail using locales used in these country codes will not be marked
# as being possibly spam in a foreign language.
ok_locales en zh
body CH_FREE /免费/
describe CH_FREE Contain Chinese Free
score CH_FREE 3.0

score SUBJ_FULL_OF_8BITS 2
whitelist_from *@lzb.ac.cn

http://johnleach.co.uk/words/archives/2005/09/15/180/