Dear QMail users,
I am a QMail newbie and I would like some advice on some qmail performance
issues.
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.
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?
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 have also noticed that some free email services like Yahoo also uses
QMail (if I'm not mistaken). They have millions of users, so I assume they
host the email service on multiple machines. How is it possible to do
load-balancing for emails on multiple machines? 'cause everyone will have
an email address like [EMAIL PROTECTED], but how does Yahoo redirect
portions of users to different machines for mail receival/sending?
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?
Sorry for my huge number of questions. Your prompt help is greatly
appreciated.
Yours sincerely,
Andy.
