> 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..
No, it doesn't. If you think it does, perhaps you've misunderstood what was described above. Note that this is still done prior to accepting the message. It's done after the DATA phase, but BEFORE the acceptance of that data.
It does miss out on the "extra benefit" of bandwidth savings, but does not defeat the spam-prevention powers of greylisting. And reducing the amount of spam in your mailbox IS the primary purpose of greylisting.
The spam still doesn't end up in your mailbox. The legitimate email still tries again. Benefits of greylisting are 99% intact.
