Need to reject null characters

[Douglas Ward]

I need to configure MailScanner or Spamassassin to reject any e-mails
with null characters in them.  We are getting null character spams
occasionally which fouls up our imap users (checking their mailboxes
through squirrelmail).  I know that postfix has a handy command for
this in 2.3 but cannot upgrade to it (due to a long and tortuous
Mandriva 2007 upgrade problem).  Is there another way to configure
this?  If not, could we request it as additional functionality in a
future version of MailScanner?  Any advice would be most appreciated.
Thanks!