Re: [exim] Cluster

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Author: Alain Williams
Date:  
To: Ian Eiloart
CC: exim-users
Subject: Re: [exim] Cluster
On Mon, Aug 17, 2009 at 11:11:04AM +0100, Ian Eiloart wrote:
>
>
> --On 17 August 2009 10:37:58 +0100 Alain Williams <addw@???> wrote:
>
> >On Mon, Aug 17, 2009 at 10:23:47AM +0100, Ian Eiloart wrote:
> >>
> >>
> >>--On 14 August 2009 17:29:12 +0100 Ian Eiloart <iane@???> wrote:
> >>
> >>>
> >>> Which is fine for MX servers. Not so good for MSA. MUAs (user clients)
> >>> don't use MX records, and don't retry even if the smtp server address
> >>> is a round robin in the DNS. At least, none of the servers that I've
> >>> tried.
> >>>
> >>
> >>Self-correction: I mean that none of the MUAs that I've tried will try
> >>alternate SMTP servers, even if the DNS gives them several IP addresses
> >>in a round robin.
> >
> >As I said: 127.0.0.1 is usually available, then rely on the local exim to
> >get it right.
> >
>
> I'm kind of assuming that we're discussing the 99.9% of users that can't
> possibly benefit from this advice because they don't have the technical
> skills.


Who sets the machines up ?
You were talking about ''badly written web apps'' -- that implies a web server,
if someone has installed that on a machine then they can install a simple exim
that knows about 2 or 3 smart hosts that it punts everything to. Thus locally
delivered mail will get to the next hop in a few seconds ... assuming that
the local machine is connected to your local network.

> Apart from which, putting mail onto a local queue that doesn't get run for
> a week is exactly the problem that I just described. All it takes is for
> the local exim to get shut down with the host just before you go on
> holiday. It's almost exactly equivalent to the MUA doing the queuing. We
> switch that off by default on our local clients so that users are made
> aware that their email hasn't been delivered.


Not at all. The local MUA (as you said) will only try one smarthost, a local
exim will try however many you specify and succeed in less than a minute.

--
Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256 http://www.phcomp.co.uk/
Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php
Past chairman of UKUUG: http://www.ukuug.org/
#include <std_disclaimer.h>