Alan Altmark wrote:
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. :-)
I'm not yet agitated enough to dig out the RFC and read it again;
whatever it does say, the fact remains that sendmail does queue and that
mail may therefore be queued. I fully expect this to be true if exim or
postfix is actually used rather than sendmail.
If mail does get queued, best deal with it. Run sendmail or whatever to
ensure any queued mail is sent when possible.
I rather suspect you must do this too if your /etc/aliaaes send root's
mail to another machine.
I happen to think that the footprint of any major MTA in this low-volume
is small enough to not worry about. I used to run sendmail (and a bunch
of other stuff) on a 8 Mb 486. I'm sure it's grown since then, but I
really don't think it uses much by way of resources unless you have a
busy mail server.
--
Cheers
John
-- spambait
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