On Wed, 13 Jan 1999, Dax Kelson wrote:
>
> Has anyone (Dan?) done real-world bandwidth measurements of how qmail
> compares bandwidth wise to sendmail/zmailer/exim/postfix?
>
> A common complaint I hear is "qmail would use way more bandwidth, then XXX
> MTA".
>
> It would be nice to point them at some number to take a look.
practically the only time this is true is where the other maiolers
compress several recipients of a message into one transfer.
assuming most messages are about 4k and a recipient is <80 bytes then
another mailer would save you about 4000 bytes of transferred data per
additional recipient at a remote site
(for each additional recipeint)
<<< MAIL FROM: <recipient>
>>> 250 OK
(plus greeting)
>>> 220 illuin.demon.co.uk ESMTP
note, this speedup only occurs where you have multiple recipients at a
site; for most lists I'm member of a site typically only have one member
on the list anyway and the difference is negligible.
In my experience network latency doesn't affect mail thoughput half as
much as:
- disk IO (moving to a logging filesystem is a gret improvement)
- memory footprint (less swapping, see above)
the bottleneck will be on the smtp-sender, and again in the scale of
things email is a really low volume acitivity in comparison to (say) web
browsing. IF network latency (as opposed to bandwidth) is a problem then
increasing remoteconcurrency gets over this.
Richard
