Martin Nix wrote:
> Our personal experience with various email servers has put us squarely
> in the qmail camp. There is a very good tutorial called "life with
> qmail" which talks you through in detail what is a bit of a mind numbing
> install otherwise. What I particularly like about it is its speed (very
> low system utilisation compared to sendmail etc) and pluggability.
>   

I do use qmail on some systems (as part of a preconfigured system) and
find it horrible to work with, but that's probably lack of experience.
I'll look up the tutorial and see where that takes me.

> Although I see you have had problems with SA we have not with qmail.
>   

I do like SA for low volume email, and we use it a lot internally. But I
am aware how long it takes to process email and I'm not sure how well it
would scale.

What has triggered this "quest" is that my exim-based hosted mail server
currently has around 2000 emails in its mail queue, the vast majority of
which are bounces or retry messages waiting to be sent on. On a regular
basis the load on the server brings the web sites on the same server to
their knees, and I have to stop that happening. There is no spam
checking on the server at present (although many domains go through
external spam checking before they reach mine). I think that one problem
is greylisting downstream, although I can't prove that (*). Either way I
want to move mail pre-processing to a different host (to which the MX
records will point), including spam checking, then using authenticated
SMTP to deliver to the existing host (which will no longer be MX listed
or accept SMTP connections without authentication).

* What I *think* is happening is that spam is getting sent with a return
address which comes through our server but is redirected by our server
to another destination, eg an account at an ISP such as Demon. The
bounce from the spam is coming to our server which is accepting it then
forwarding it to the ISP which is greylisting (giving a temporarily
unavailable response on first connect) causing my server to queue the
mail for a period then retrying it. Multiply that by a few thousand and
you get to where I am right now.

How does exim decide when to retry queued mail? Is that a periodic
process that runs at certain times? If it is that would explain the
fairly predictable slowdown of the server, eg at around 2:20pm every day.

Anyway, where this thread started was a desire to set something up
internally as an educational exercise before looking at moving it to a
hosted server asap after that.

> Distro wise, you should probably go with what you are familiar with,
> personally I would use Fedora Core 6, if the box is pretty resource
> stretched then maybe Fedora Core 4 would be a better bet (I'd steer
> clear of Fedora 7 that is coming out today for time being)
>   
Agreed about going with what I know, so that probably means Ubuntu these
days.

-- 
Mark Rogers // More Solutions Ltd (Peterborough Office) // 0845 45 89 555
Registered in England (0456 0902) at 13 Clarke Rd, Milton Keynes, MK1 1LG 


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