On Fri, Jul 03, 2009 at 02:30:10PM +0200, Jozsef Kadlecsik wrote: > > > 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, protocol itself is just the communication between MTAs (it does not store anything itself, MTAs which uses the SMTP can/must store things while using SMTP to communicate with other MTAs).As proxy level firewalls has got proxies (like Zorp) for SMTP without having any queue. I would like to do this, and I have the suspect I am a bit off-topic now, because it's not so postfix related question then. > 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. For example PowerMail do this. It hasn't got queue by design. It's a "mailstore" MTA, it can only accept mail. It simply does store mail to the final destination (user maildir for example) instead of having a separated queue file - which will be read then again to store into the user's mailbox or whatever even on the same system - it does the job directly. Of course PowerMail is not a general purpose MTA like Postfix, its usability is limitid to implement the "final destination" of mails on the "mail store" systems. For me it does not make sense that an MTA can accept mail which won't be able to store that mail then, it's better to reject then. Especially because generating NDRs needs more work, using large queues requires more resources, and also a generated NDR is better to be generated as near to the sender as possible: I simply does not accept mail if it would be over quota, so the sender's MTA will generate NDR if needed. It's better for the user too: maybe the sender's MTA uses the language of the sender user, or they are more comfortable with their own "style" and so on. -- - Gábor
