请教！postfix + amavisd-new + spamassassin的问题

jimson

postfix + amavisd-new + spamassassin ，出现了如下问题：

察看maillog：

Oct 17 21:27:56 mail amavis[1634]: (01634-01) FWD via SMTP: <xxxx@163.com> -> <xxxxx@slave.bbb.net>, BODY=8BITMIME 250 2.6.0 Ok, id=01634-01, from MTA([127.0.0.1]:10025): 250 Ok: queued as 183F012EE8A
Oct 17 21:27:56 mail amavis[1634]: (01634-01) Passed SPAMMY, [220.181.13.67] [61.150.xx.xxx] <xxx@163.com> -> <xxxxx@slave.bbb.net>, Message-ID: <4534DA3F.000113.19623@bj163app67.163.com>, mail_id: GExoS+mJi9Ry, Hits: 8.049, queued_as: 183F012EE8A, 17444 ms
Oct 17 21:27:56 mail postfix/smtp[1644]: 9469212EE5C: to=<xxxxx@slave.bbb.net>, relay=localhost[127.0.0.1], delay=18, status=sent (250 2.6.0 Ok, id=01634-01, from MTA([127.0.0.1]:10025): 250 Ok: queued as 183F012EE8A)


好像spamassassin是起了作用的，并查出是垃圾邮件：Passed SPAMMY

但是奇怪的是，我已经在 amavisd里面设置了：
$sa_spam_subject_tag = '***SPAM***';

邮件的标头却就是没有加上***SPAM***，同时，也没有看到有spamassassin的report信息，spamassassin究竟干什么去了啊？