> 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.
This is bad practice. As stated before, it will not scale well at all.
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.
Not true. We're seeing spam messages are becoming smaller and/or it is written in a way that causes it to hit hardly any rules. These messages score around the 1 or 2 points mark and they will flow through your implementation easily whereas if you weren't doing pre-queue scanning, the greylisting approach would of blocked it..
Its all fine and well to implement pre-queue scanning of mail if you have a small site to manage. It does not work with large volumes of mail..
Cami
