sa-learn 出現錯誤?

[kennyk]

nat:~# /usr/bin/sa-learn --showdots --spam --mbox /var/spool/mail/spam
Parsing of undecoded UTF-8 will give garbage when decoding entities at /usr/share/perl5/Mail/SpamAssassin/HTML.pm line 182.
....
Learned from 0 message(s) (4 message(s) examined).

是不是少裝了什麼東東呀?

各位大大多多賜教, 感激不盡!