> I have a question about qmail regarding its mail handling capacity.....
> How many remote emails can qmail send simulataneously, assuming it is run
> on a Dual-CPU PIII 500Mhz with 512Mb RAM and a SCSI hard disk? The
internet
> bandwidth is 10 Mbps.
A lot. : )
There is a hard-coded limit to the numebr of concurrent remote sessions,
somewhere around 200, if I recall, but you can certainly increase that in
the source, if necessary. Below 200, it is controlled by a "soft limit"
contained in the file "concurrencyremote". I'm sure that your machine could
handle 200 with ease.
> If I run 2 parallel processes that sends out emails, does it mean twice
the
> amount of emails get sent off simultaneously? if so, does that mean the
> more processes I run in parallel, the more emails get sent off at the same
> time? or will most of the emails get stored in the queue?
As long as you aren't maxing out CPU or bandwidth, then yes, sending them
in parallel is better. That way, things like waiting for DNS lookups don't
kill your performance. That's why qmail spawns a new instance of
qmail-remote for each message to be delivered.
> What is the general number of emails that a machine with the above
> specifications can send per second/hour/day? How do I fine-tune it to send
> off millions? I only know of changing the "concurrencyremote" figure in
> /var/qmail/control/concurrencyremote. I set it to 100 for testing. What
> should be a good figure assuming that I will do free email hosting on the
> server for hundreds of thousands of users?
I'd watch your bandwidth, but I'd bet that 200 would be perfectly
reasonable. I've raised it to 100 on a Pentium 233 w/ 512k bandwidth, and
it definitely speeded things up quite a bit. 500 emails took ~45 seconds to
clear, perhaps a bit less. That's about a million per day. With your
system, you should be able to handle more, although sooner or later, you'll
hit the major limiting factor: I/O. It sounds like you're just starting
up, so you should be fine for some time. Once things get severely large,
you'll need to at least go to a hardware RAID setup, with multiple disks on
multiple channels/controllers to get the throughput.
> Another question is about the Mail header. What is the header that I
should
> add into a generated email so that undelivered/bounced emails go to this
> specific email address instead? For example, I send an email to
> [EMAIL PROTECTED], it will by default bounce back to my sending
> account. How do I make it bounce to another account instead? Should I use
> Errors-To:, or Undeliverables-To: or any other header?
I've heard of "Bounce-to:" being used, but I'm not hip on the RFC's like
others on the list. : )
steve
