Tom writes:
[ about qmail ]
> It is no longer developed, and no one is
> interested in fixing its bugs. I particularly hate its RFC violating
> retry behaviour. If Qmail receives a 4xx code on initial connect it
> retries without any delay until it doesn't get a 4xx!
You are making false statements, in reckless disregard of the truth.
Please cut it out.
---Dan
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From: sl@??? (Stuart Lynne)
Newsgroups: list.exim-users
Subject: Re: [Exim] Re: Very large mailing lists (Exim vs Isocor)
Date: 10 Apr 2000 00:50:16 -0700
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In article <38F15807.8EBFB951@???>,
Dave Cinege <dcinege@???> wrote:
>Jason Gunthorpe wrote:
>>
>
>> 30K messages/hour is only 8 messages/sec. Our lists (using qmail) average
>> that when they are going, and peak out at 13msg/sec. This is all on a P133
>> w/64M ram and IDE disks. Primarily we are disk bound (on the fsyncs of the
>> user list)
>
>Damn....what OS, and does it do anythign else besidesact as MTA?
>
>> I *expect* postfix and zmail can both get similar numbers, give or take a
>> percent without too much trouble. Exim/sendmail I think it would be hard
>> to push it up to those concurrency levels.
>
>Why not with exim?
>
>> The only reason we get those rates is due to the 240 concurrent outbound
>> delivery processes - that is the critical factor when you are doing lists,
>> you want to maximimze concurrancy so that slow remote hosts do not hold up
>> the works, we typically have over 50 'slow' connections that hang around
>> and gum things up.
>
>Exim can be set to spawn up to X amount of processes per queue and up to a max
>of X concurrent queues during delivery. Does this not put it on par?
If we can believe the author of postfix, mail delivery in a balanced server
boils down to disk I/O's per second. If you reduce the number of disk I/O's
per second it takes to deliver mail you will be able to handle a larger
workload. Given this metric the current consensus seems to be that postfix
is leading by a nose, followed by qmail. Exim follows up not terribly far
behind and sendmail is probably not terribly farther behind that. It is
seems unlikely that there is as much as a 2-1 difference between the fastest
and the slowest.
So I'll make two observations. First given the number of disk I/O's you can
purchase today, it's probable that you need a fairly impressive workload
before you exceed any of the above (many hundreds of thousands of messages
per day). Second if you actually have a workload that big, you are probably
planning on what to do next. I.e. how to spread the load across multiple
servers.
So until your workload gets truly immense (many millions of messages per
day) your choice of MTA is probably more constrained on what fits your
environment best. What are your administrators most comfortable with etc.
BTW I'll put another plug in for exim. It is fairly trivial with exim out of
the box to support delivery of mail across multiple servers irrespective of
domain using (for example) ldap or mysql.
--
Stuart Lynne <sl@???> __O
<http://www.thinlinux.org> _-\<,_ 604-461-7532
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