John D. Hardin writes: > On Mon, 19 Jun 2006, Steven W. Orr wrote: > > > =>> Is it worthwhile to try to convince the SA dev > > =>> crowd to add greylist functionality? > > > Neither. What I'm looking for is a rubust way to say: "I haven't > > seen mail from this guy before so I'm going to reject his email > > with a 450 error code. If email from him tries for delivery after > > (let's say) four hours, then I will accept it and nevermore will > > this guy have a delay in sending me mail." > > That's the common definition of "greylisting". > > I think the suggestion to add it to SA misses a basic fact: the > mail has *already been received in its entirety* by the time SA gets a > chance to see it. What's the point in greylisting then? > > Proper greylisting is done early in the SMTP exchange, at the point > the DATA command is sent and the sender and recipients are known but > before the message itself has been received. I use milter-greylist to > do this and it works well.
Yep -- that's the key point -- as far as I know it's illegal (in SMTP terms) to offer a 421 after DATA. --j.
