SpamAssassin custom headers

[Jeffrey Haas]

Is it possible to ask SpamAssassin to create a custom header and have it 
appear in a message processed by MailScanner?

I'd like to be able to view the detailed RBL report for a message to see 
which address triggered the RBL test by adding something like:

add_header all RBL rbl=_RBL_

to MailScanner's etc/spam.assassin.prefs.conf file.

Looks like MailScanner only includes its own headers by default.  Is 
there a way to pull a header in from the SpamAssassin report?

Thanks for any info.

--jeff