Rodney Broom <[EMAIL PROTECTED]> wrote:
> > Charles Cazabon <[EMAIL PROTECTED]>
> >> D Rajesh <[EMAIL PROTECTED]> wrote:
re: batched recipients per-MX or per-domain
> DR> > I guess this speeds up the mail delivery amazingly !!!!
>
> CC> No, it slows it down tremendously. That's why qmail doesn't do it.
>
> ===> If you send a single messager to a given domain, then the activity on
> your side should look something like this:
>
> - Lookup recipient domain.
> This requires getting the current MX for the recipient.
No network load after the first one; it will be in your DNS cache. You are
running a local DNS cache on every mail server, aren't you?
> - Open a socket to the mail server for the recipient domain (connect).
On a good OS, this is negligible, and qmail is very efficient.
> - Tell the recipient mail server who you are. (trivial, but existant)
> - Send the mail (headers and body)
> - Close the socket connection.
None of this is different with per-domain batching.
> According to the input from Charles, qmail repeats this entire process for
> EVERY message sent to a given domain.
Yes. It's faster because it parallelizes well, and you have fewer round-trip
waits. With batching, you have to do:
send one RCPT
wait for response
send next RCPT
wait for response
...
By the time you've listed ten or twenty recipients, qmail has finished
delivering all ten or twenty copies in parallel.
> Hmm, only one copy of the body got sent to 5000 recipients. Let's see, 5000
> times 1K... Hey, that's 5 megabytes!
qmail is designed for well-connected hosts. If you want to send a message to
20k recipients over a narrowband line, don't use qmail.
> See, we've missed 5000 name lookups and socket connections. I'll admit that
> a decent name server helps this. Also, that creating a socket isn't very
> expensive on today's hardware, but it's at least a little bit of the load.
Not on my systems -- qmail simply is a negligible load on a decent OS, even
when sitting at a constant concurrencyremote of 100-150.
Charles
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Charles Cazabon <[EMAIL PROTECTED]>
GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/
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