On Thursday, 08/03/2006 at 09:56 AST, David Boyes <[EMAIL PROTECTED]> wrote: > > As I understand it, SMTP is a store-and-forward proposition, Since > some > > MUAs (and in particular the mail command) cannot handle failure, then > > the MTA _must_ accept the initial submission. > > No, it doesn't *have* to. It's *desirable*, but an implementation that > does not queue is completely conformant to the SMTP protocol spec if it > does not do so. The SMTP protocol is connection-oriented like all the > other TCP services -- no store and forward assumption at all. Queueing > is a feature that is implemented by particular applications that provide > the protocol support, but is not required by the spec. Is queuing > useful? Sure. Is it required? No.
You know, I was as positive as you are until I read what RFC 2821 (4.5.4.1 Sending Strategies) has to say: "In a typical system, the program that composes a message has some method for requesting immediate attention for a new piece of outgoing mail, while mail that cannot be transmitted immediately MUST be queued and periodically retried by the sender." A pox upon the authors. It confusingly uses the word "typical" and "MUST" in the same sentence. I fear the "typical" part applies only to the attention-getting device, allowing for I'll-scan-the-input-queue-occassionally implementations (ok for batch). It is hard to justify an accidental use of MUST. Your lawyers can call my lawyers and do lunch. :-) But the rest of that section in the RFC would leave me to believe that "more sophisticated and variable strategies" would be permitted in the queuing arena as well. [Reasonable man theory] Alan Altmark z/VM Development IBM Endicott ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
