Re: MTA or SMTP proxy?

On Fri, 3 Jul 2009, Gábor Lénárt wrote:

> On Fri, Jul 03, 2009 at 09:55:40PM +1000, Barney Desmond wrote:
> > > Recently I am thinking of reimplementing our MX servers. Of course rcpt
> > > check is a must, also I should not generate NDRs later, I should only accept
> > <snip>
> > 
> > This is all very standard behaviour for an MTA. Recipient checking is
> > a very common task for most Postfix users. Regardless of what you
> > expect or want, SMTP is a store-and-forward protocol - queues are a
> > strong component for an MTA.
> 
> I don't think so, SMTP itself is just a protocol, you can use it without
> having and storage too. It's another question that how useful it is then ...

SMTP is a store-and-forward protocol, it does require queues. You cannot 
simply wave aside this requirement.

I think it cannot be solved with an SMTP proxy "without queues" either: 
the final destination must queue the message first. After that it can 
attempt a local delivery, which may fail, for example due to the user 
being over quota. Therefore at the proxy side you also have to maintain 
the mail queue.

Best regards,
Jozsef
-
E-mail  : kadlec <at> blackhole.kfki.hu, kadlec <at> mail.kfki.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : KFKI Research Institute for Particle and Nuclear Physics
          H-1525 Budapest 114, POB. 49, Hungary