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Re: ZMailer "hangs up" on message queues...

On Thu, Jul 26, 2001 at 10:26:47AM -0700, Michael Loftis wrote:
> It is not a spam engine.  [...]
> We refuse to allow any suspicious lists to be pushed out through our
> system, we offer personalization and tracking for our clients.  If we
> lose even a few thousand messages that translates into a lost client. 
> So yes 40 messages a second can to be useful.

  40 single-recipient unique messages a second ?

Pushing out lists is usually simpler is you send exactly the same to
a larger number of people -- 2000-3000 recipients in each message.
Pre-sort the addresses (case insensitively) by the recipient domain,
and Z will deliver all recipients with same domain at the same time.

Doing personal customized email is ... whole different basket of problems.

System performance limitations have been learned to be around $POSTOFFICE/
directory hierarchy operations.  To a large extent that is a matter of
lock contention, and disk-IO performance.

Inventing new radical approaches might be necessary if performance boost
beyond current levels is called for.  I think of moving the queue from
easy to manage "files in directory" to some sort of "multi-writer database
in raw partition"...

  ... but is it really necessary ?
Can't the load be distributed over several boxes ?

Instead of special ultra-fast IO disks and such stuff, just have identical
simple machines by dozen, and distribute the job into them all ?
(My usual approach in networked problems is just that.)
((If you need some *state* kept at global level, you are screwed
  by the performance (or lack, thereof) of the global state database.))

> I have a ListServ type farm elsewhere that handles about 75/second but
> thats raw recipients, the number of envelopes is probably closer to 15
> or so a second, and number of deliveries a second (Seperate envelopes
> exploded) is close to  around 38 a second. 
> 40 messages a second is indeed useful, it's roughly a 10Mbit pipe too
> (depending on message size of course, but the average puts it right
> around 10Mbit including TCP/IP and session overhead)
> :)

/Matti Aarnio	<mea@nic.funet.fi>
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