Author: Jason Gunthorpe Date: To: exim-users Subject: Re: [Exim] Re: Very large mailing lists (Exim vs Isocor)
[yuk, who is running the broken news gate]
On 10 Apr 2000, Stuart Lynne wrote:
> 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
This is primarly true for *local* deliveries. For lists disk IO *and*
network IO factor into the equation very strongly. You can control your
disk IO, but you have no control over the conditions of remote hosts.
That is why it is critical to have a huge number of concurrent
connections, to keep your network IO rate high.
> 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
We do 500,000/day on a Fujistu IDE disk, we have not yet hit the disk IO
limit, but this box is a list server so it only does disk IO to update the
message status. For qmail we don't split messages, a single message can
have tens of thousands of recipients. It seems to work better like that.
> 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
For local delivery I fully agree, exim is wonderfull it has all kinds of
nice features that make it very nicely suited for local mail. Just don't
confuse lists requirements with other uses of MTAs :>