垃圾郵件過濾

1. postfix 雖可過濾字串，來阻擋垃圾郵件，但當郵件內容以 base64 編碼時，卻無法動作。
2. 安裝 spamassassin

   [root@mail ~]# yum install spamassassin
   

3. 編輯設定檔

   [root@mail ~]# cat /etc/mail/spamassassin/local.cf
   # These values can be overridden by editing ~/.spamassassin/user_prefs.cf 
   # (see spamassassin(1) for details)
   
   # These should be safe assumptions and allow for simple visual sifting
   # without risking lost emails.
   
   required_hits 5
   report_safe 0
   rewrite_header Subject [SPAM]
   blacklist_from	*@yahoo-inc.com
   blacklist_from	*@goisa.it
   blacklist_from	*@moopex.cz
   

4. 查詢設定檔編輯說明

   [root@mail ~]# man Mail::SpamAssassin::Conf
   

5. 新增 spamd 群組及帳號

   [root@mail ~]# groupadd spamd
   [root@mail ~]# useradd -g spamd -s /bin/false -d /var/log/spamassassin spamd
   [root@mail ~]# chown spamd:spamd /var/log/spamassassin
   

6. 編輯 postfix 的設定檔，將 spamassassin 整合進 postfix。

   [root@mail ~]# vim /etc/postfix/master.cf
   [root@mail ~]# grep 'spamassassin' /etc/postfix/master.cf -B4 
   # ==========================================================================
   # service type  private unpriv  chroot  wakeup  maxproc command + args
   #               (yes)   (yes)   (yes)   (never) (100)
   # ==========================================================================
   smtp      inet  n       -       n       -       -       smtpd -o content_filter=spamassassin
   --
   #
   #mailman   unix  -       n       n       -       -       pipe
   #  flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
   #  ${nexthop} ${user}
   spamassassin unix - n n - - pipe flags=R user=spamd argv=/usr/bin/spamc -e /usr/sbin/sendmail -oi -f ${sender} ${recipient}
   

7. 啟動 sapmassassin 前更新 spam rules。

   [root@mail ~]# sa-update && /etc/init.d/spamassassin restart
   

8. postfix 及 spamassassin 重新載入或啟動

   [root@mail ~]# /etc/init.d/postfix reload
   Reloading postfix:                                         [  OK  ]
   [root@mail ~]# /etc/init.d/spamassassin restart
   Stopping spamd:                                            [  OK  ]
   Starting spamd:                                            [  OK  ]
   

9. postfix 及 spamassassin 重新載入或啟動

   [root@mail1 ~]# vim /etc/mail/spamassassin/custom_rule.cf
   header LOCAL_EVERYTHINGYOUNEED_RULE Subject=~ /Everything you need, you can find here/i
   score LOCAL_EVERYTHINGYOUNEED_RULE 3.0
   describe LOCAL_EVERYTHINGYOUNEED_RULE Everything you need
   [root@mail1 ~]# spamassassin -D --lint