Re: [exim] is there a way to prevent host based defer...

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Author: Ian Eiloart
Date:  
To: Jeff Boehlke, exim-users
Subject: Re: [exim] is there a way to prevent host based defer...


--On 3 October 2007 17:12:48 -0400 Jeff Boehlke <Jeff.Boehlke@???>
wrote:

> I have been searching the FAQ and the archive and decided it was time to
> post to the group.
>
> Here is the situation: I am using Exim 4.63 on RHES. We send all our
> outbound mail to a third party external system which is load balanced
> and geographically dispersed.
>
> The Exim daemon is set to start a queue runner every minute (exim -bd
> -q1m)
>
> In my config I am also using the following:
>
> queue_smtp_domains = *
> split_spool_directory
> queue_run_max = 10
> remote_max_parallel = 1


The manual has this to say:

    Exim processes the waiting messages in an unpredictable order. It
    isn’t very random, but it is likely to be different each time, which
    is all that matters. If one particular message screws up a remote MTA,
    other messages to the same MTA have a chance of getting through if they
    get tried first.


but, it also says:

    When [split_spool_directory is set], the queue is processed one
    sub-directory at a time instead of all at once, which can improve
    overall performance even when there are not enough files in each
    directory to affect file system performance.


Perhaps the order of processing doesn't randomise sub-directory selection.
What are your queue lengths? Perhaps you don't really need
split_spool_directory to be set.


>
> And my last router looks like this:
>
># The following router will send to remote smart host
> send_to_remote_smart_host:
> driver = manualroute
> domains = ! +internal_domains
> transport = remote_smtp
> ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
> route_list = * remote.smart.host
> no_more
>
> recently, we have had delays when sending to certain resolved host IP's
> on the third party system. When that happens I start to see a backup in
> the queue with several messages showing up as deferred in the queue.
> Many times the initial problem is with a message with a large
> attachment, but all the other messages that were deferred seem to stay
> on the queue skipping retry as long as the original offending message is
> still unsent - and that seems to be the only message that is retried.
>
> What I am assuming is happening, is that Exim is deferring all other
> messages that it determined were bound for the same host so they all go
> into retry without having tried to deliver the message at all. Is there
> a way to change that behavior?
>
> Thanks,
> Jeff




--
Ian Eiloart
IT Services, University of Sussex
x3148