I may not understand the greylisting concept fully. I thought that the idea was to short circuit receipt of the entire message until the second attempt. How do you get a spam score from SA prior to receiving the message?
MTA layer integration.. It scans at the end of the SMTP DATA phase prior to accepting delivery. Messages can still be 4xx'ed or 5xxed at the end of the DATA phase, so this does in fact work.
Completely defeats the point of greylisting..
