Re: Documentation of big "mail systems"?
On Wed, 13 Oct 2004 07:18, Stephane Bortzmeyer <firstname.lastname@example.org> wrote:
> I'm currently writing a proposal for a webmail service for, say, 50
> 000 to 500 000 users. I'm looking for description of existing "big
50K isn't big by today's standards.
An ISP I used to work for has something like 1,300,000 users. They have two
SMTP machines for outbound email which do virus scanning (to stop customers
from sending viruses). They have four SMTP machines for inbound mail which
do anti-spam and virus scanning (RAV anti-virus and Qmail). Those four
machines send mail to the back-end machines according to data in OpenLDAP
(about four slave OpenLDAP servers and one master). There are six back-end
machines for mail store that run Qmail for delivery and the Courier POP and
IMAP servers, all data on user mail directory and password is in LDAP. The
back-end servers use ReiserFS mounted noatime for storage.
When a user connects via POP or IMAP they get to a Perdition server, there are
three Perdition servers behind Cisco LocalDirectors (for reliability and load
balancing) which proxy IMAP and POP to the correct back-end servers after
doing an LDAP lookup. The Perdition server machines also run Apache and IMP
for webmail, the webmail instance uses Perdition on localhost for IMAP
The machines are pretty much all Dell servers with 2*2.8GHz P4 CPUs, about 4G
of RAM, and 4*U160 disks in a RAID-5 array (with one hot spare).
The machines were all running 2.4.2x last time I was there, but they may be
moving to 2.6.x now.
SAN and NAS are best avoided IMHO.
http://www.coker.com.au/selinux/ My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/ Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/ My home page