huge email system

[Bill Campbell]

On Fri, Nov 21, 2003, Bill Vermillion wrote:
>They all laughed on Fri, Nov 21, 2003 at 17:28  when David said:
> 
>> Hello -
>
>> We need to build a stable, redundant, and speedy email system
>> that will last for a few years. We need to handle about 500,000
>> emails per day. We have about 30,000 users, so we need a lot of
>> storage.
>
>30,000 users with only 500,000 emails per day.  I say that based on
>running a small ISP with a few hundred users and see large mail
>volume.  All are business accounts.  
>
>I'll let others comment on the rest, but I think 500,000 emails per
>day may be underestimating things.  That's only 20 emails per user
>per day.  

I don't think that's far off.  We have a customer who's a regional ISP with
about 2,000 dialup customers, and they average about 13,000 e-mails in and
out in a 24 hour period.  That's handled easily on a 550MhZ PIII with 128MB
of RAM running Caldera eServer 2.3 Linux, and a load average of about 0.33.
They're running postfix and courier-imap for the e-mail.  This same system
is running a fair number of web sites on apache as well.  This machine has
been running non-stop since October 2000 (hence the old version of Linux),
rebooting only for power failures and equipment moves.

Our main mail server here handles far fewer incoming mail messages, but
delivers about 35,000 outgoing messages daily for several technical mailing
lists, and it's a secondary MX server for most of our customers.  It's
running on an even older machine, a 350MhZ Pentium II running Caldera
OpenLinux 2.3.  The machine it replaced handled similar mail loads from
1995 through 2000, running on a Pentium 90 with SCO OpenServer.

>As to last a few years - who knows.  In the past year I've seen
>such an overall increase in mail volume that now I'm looking to get
>new servers with more CPU power.  It's not disk size that is the
>problem but the in-coming and out-going traffic that is killing the
>CPU.

Running programs like spamassassin will be a major factor.  Checking for
worms that attack the Microsoft virus, Windows, can be done very
efficiently if one looks only for executable attachments.  It gets a bit
more expensive if one runs wormware such as McAfee's uvscan to pick up
things like Word and Excell macro worms.

Bill
--
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