[CentOS] spamassassin with postfix/dovecot

I'm trying to install spamassassin on a postfix/dovecot server,
running CentOS-6.4, following the instructions at
<http://wiki.centos.org/HowTos/Amavisd>.
I think I have taken all the steps indicated,
and the configuration seems to pass the tests suggested,
although the response is much more sparse than that described:
------------------------
[tim at alfred ~]$ telnet localhost 10024
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 [127.0.0.1] ESMTP amavisd-new service ready
helo localhost
250 [127.0.0.1]
quit
221 2.0.0 [127.0.0.1] amavisd-new closing transmission channel
Connection closed by foreign host.

[tim at alfred ~]$ telnet localhost 10025
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 alfred.gayleard.eu ESMTP Postfix
helo localhost
250 alfred.gayleard.eu
quit
221 2.0.0 Bye
Connection closed by foreign host.
------------------------
I tried sending the GTUBE spamassassin test-
mail given,
but I got the error message:
------------------------
Failed to transport message. The message content was not accepted.
The server responded: "Message refused"
------------------------
But I see no evidence that email is being processed by spamassassin;
and I don't see anything in any of the conf files
setting that up.

Any suggestions or elucidation gratefully received.

-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland