On Thursday, January 09, 2003 11:32 PM [GMT+0530=IST],
brian@??? (Brian Kendig) wrote:
> I've got a couple of questions about SMTP pipelining...
>
> First of all, what is it? My understanding is that it's the practice
> of sending a whole bunch of SMTP commands all at once without waiting
> for a response between each one. Is that right?
_if_ the receiving server advertises PIPELINING in response to an EHLO,
the sending client will pipeline.
qmail, postfix, exim, sendmail 8.12.x and quite a few windows MTAs
implement this.
> Second, do only spammers to this, to exploit the fact that most mail
> servers will process all the commands in sequence so the spammer can
> move on to the next mail server more quickly?
The point is that spamware often sends a HELO - and pipelines away to
you rather than waiting for a 250 ok. Postfix has something called
reject_unauth_pipelining to take care of precisely this sort of thing.
srs
