Re: [Exim] Questions about SMTP pipelining

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?

SOME commands can be bundled, not all, you can't take the whole
SMTP-dialog, fire it to the server and hope that it goes well.

Pipelining helps to work arounds TCP-latency.

> 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?

Many (most/all?) mailservers support pipelining, in fact exim does.

> Thirdly, if it *is* a spamming practice, does Exim automatically see
> when it's happening and reject the message? Or is there a way to
> configure Exim to do this?

You can enable exim to enforce proper use of pipelining (only allow
special packs of commands in a row) and disconnect if the other server
misbehaves.

ciao