Re: alternatives to ETRN

[Matti Aarnio <mea@nic.funet.fi>]

> Hi gang,
> 
> 	We have quite a few dialup users who for some warped reason like to
> do SMTP over their connection, but don't want to stay online for prolongated
> periods of time.
> 
> We had a hack where they could send a message to an address and in response
> sendmail would rerun the whole queue, sending the user's message if he was
> online.
> 
> This feature placed an unnecessary burden on our mailserver what's already
> swamped, so I wonder if anyone has a solution for zmailer where it would try
> to resend mail for a specified domain if it gets a specific mail?

	For quite a while ZMailer's scheduler has operated in such a way
	that if there is a new message going to  Channel-C/Host-H, and the
	system has resources available to run a new (or recycled) transport
	agent, then appearance of the new job will run ALL accumulated jobs
	to that particular target at the same time.

	Defining parameters:
		interval=1h
		retries="12"
	would make sure that any such thread be retried only every 12
	hours, although (as I said above) appearance of a new message
	will also cause run attempt.

	What ever, it will use up only one transport agent, which operates
	independent of all of the other message flows going around.
	That is, it will not cause significant slowdown to the system, not even
	when there are thousands of messages going to that one thread...
	(All this assuming you don't have too many of such targets with huge
	 queues in your system -- like several dozens of them ...)

	With  2.99.49p5  there is configuration flag "queueonly", which
	just accumulates the target thread(s), but will never automatically
	start the queueing.  Instead, the target Host-H MUST be triggered
	by explicite "ETRN Host-H" command thru the smtpserver.

	This will, of course run all channels with Host-H, however I thought
	that to be a minor nuisance instead of demanding things like "it must
	be in 'smtp' channel" -- because I think it will be easiest to have
	explicite 'route' entry telling something like:
		target.host	smtp-etrn!
	and associated  scheduler.conf  target:
		smtp-etrn/*
			...
			queueonly
			command="smtp -c smtp-etrn ..."

	For that route example the necessary ETRN is:
		ETRN target.host

> Sorry for the long winded message, my english still sucks.

	Long ?  I can hardly think of shorter form to describe your
	question.   Your english appears rather good, as even I do
	make mistakes there.  In my native language we don't have
	these 'meaningless' fillers like 'a', 'an' and 'the', and
	thus I tend to occasionally forget them..  ( And all languages
	with gender differentiation are also difficult, Finnish is
	definitely gender-equal -- people/animals (he/it) difference
	exists, but there is no male/female (he/she) difference.
	OTOH, our head of parliament is a woman, while her title is
	'chairman' ...)  (( But this is long-winded non ZMailer topic. ))

> 	Imre

/Matti Aarnio <mea@nic.funet.fi>