On 20 December 2016 at 15:48, Jeremy Harris <jgh@???> wrote:
> > From the example in the Specification it looks like when the threshold is
> > reached I use *delay* to introduce a delay. However *delay* takes a
> > standard Exim time interval: an integer number of seconds, minutes,
> hours,
> > days or weeks.
> >
> > Is there a way of using a *fraction* of a second for the delay — eg, 0.5
> > seconds
>
> No.
>
> Beyond a deliberate call to some external facility.
> Builtin perl, possibly.
>
Ah, OK… That's sad. I was hoping to allow an initial burst of messages
through (tested with a *ratelimit* condition in the acl_smtp_mail) and then
use *delay* to slow down throughput to around 250 messages per minute.
Ignoring reception tie of the message itself, that would require a delay of
around 60 seconds / 150 = 0.24 seconds.
However if the minimum delay that can be waited is only 1 second that
effectively caps the ongoing throughput at a rather low 60 messages per
minute — 60 seconds / 1 second delay = 60 messages per minute.
> > — or would I have to look at using the old-style
> > *smtp_ratelimit_{hosts,mail,rcpt}* options instead to achieve this, with
> > the disadvantage that they only apply within a single connection?
>
> ... and also offer no finer granularity.
>
Are you sure? That's not what the Specification seems to say; in the *Main
configuration* section it specifically says (emphasis mine) for
smtp_ratelimit_hosts:
An initial time delay. *Unlike other times in Exim, numbers with decimal
fractional parts are allowed here.*
…
A factor by which to increase the delay each time.
…
For example, these settings have been used successfully at the site which
first suggested this feature, for controlling mail from their customers:
smtp_ratelimit_mail = 2,0.5s,1.05,4m
smtp_ratelimit_rcpt = 4,0.25s,1.015,4m
The first setting specifies delays that are applied to MAIL commands after
two have been received over a single connection. *The initial delay is 0.5
seconds, increasing by a factor of 1.05 each time.*
That strongly implies it provides delays of fractional seconds; there's
nothing to say these fractional times are rounded (up? down?) to an integer.
That's why I was hoping there might be some way I'd not found of doing
fractional delays when using the new and improved ratelimit option instead
of the old-style smtp_ratelimit_* options.
Cheers,
Mike B-)
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