[Mimedefang] SMTP error return after DATA?

[Myles Uyema]

I've got spamassassin tagging spam now, but I want to try taking this a 
step further.  I want my mail server to reject the DATA portion of the 
e-mail if spamassassin deems it as spam.

action_bounce() seems to be almost the function I'm looking for, but it 
sounds like the mail is accepted and then a new bounce e-mail is drafted.

Is milter/mimedefang granular enough to tell sendmail to reject the mail 
during the SMTP connection after the DATA portion is complete?

The RFC stipulates the following return codes are available for the DATA
stream input:
            DATA
               I: 354 -> data -> S: 250
                                 F: 552, 554, 451, 452


MAIL FROM:<valid e-mail>
220 OK
RCPT TO:<valid e-mail>
220 OK
DATA
354 OK
spam spam spam spam
spam spam spam spam
spam spam spam spam
.
552 No spam for me!


Is this possible with action_bounce, filter_begin, or filter_end?