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Re: POP3 and SMTP server for an ISP

On Friday 23 February 2001 22:21, Richard A Nelson wrote:
> On Fri, 23 Feb 2001, Russell Coker wrote:
> > Postfix should work if you use something like maildrop for delivery.
> > Apparently you can hack wrapper scripts to check LDAP or SQL for user
> > details.  I'm investigating this myself now.
> sendmail 8.11.2 comes with LDAP support (not SQL) built in and can use
> maildrop for delivery.  That leaves the mail queue as the bottleneck,
> and fortunately, 8.11.2 supports multiple queue directories (this
> support is nicely extended in the 8.12 beta series)

I would be surprised is the mail queue was a real bottleneck on actual 
systems.  If installing a serious mail server I would configure two hard 
drives in a RAID-1 array for the mail queue.  For all the access to the queue 
there will be more access to the spool.

> > if you have to FSCK them you can do it in parallel.  Also having two
> > separate file systems should speed up delivery on SMP machines (haven't
> > tested this theory though).
> but only if you can have multiple queue runners right?

Multiple queue runners might be needed if the machine does nothing but 
deliver mail.  But that isn't the case.  People will also be reading mail via 
POP, reading mail via IMAP and moving it between folders etc, running 
webmail, etc.
In fact it might be a benefit to have the queue as a minor bottleneck.  The 
queue only needs to be fast enough to take twice the amount of mail received 
over the course of a day.  If something strange happens (such as a day long 
network outage that prevented communication with hotmail and AOL gets fixed 
and allows some huge queues to be emptied on you) then you probably don't 
want incoming mail to take so much resources that POP goes slow!

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/projects.html Projects I am working on
http://www.coker.com.au/~russell/     My home page

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