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Re: Mail servers for large numbers of users

On Sat, 11 Dec 1999, Jason Gunthorpe wrote:

> That is why you integrate the proper security measures into your IMAP
> daemon - for instance you could have to chroot to the proper user
> directory so that it cannot access files ouside that area  then have it
> run as not-root so it cannot chroot out.

Right, there are LOTS of ways to make if POSSIBLE but not feesable. If you
have >64K users you must expect that some percentage of them are active at
any given time. If you assume that only 5% are currently logged in to
their email directory (I leave my machine in email at all times while I am
logged on) then you are talking about >1000 users currently logged in and

If the application is for some organization that has regular business
hours, figure nearly 100% of your users being online during portions of
the day.

This is just too much for one system to handle without risking outages. It
is also too much risk of one problem denying the entire organization of
email. Better to spread fewer users over more systems.

The other thing is that if it takes more than a few working hours of time
to set up such a monolithic approach, you have already spent more money
than an additional system would cost you. Now you are in a situation where
you have spent more money for a system that places all eggs in a single

I would not want 75,000 users logging into a single box for all of the
email for an organization or project or even for some online email
service. It would be absurdly slow and a potential disaster. Better to
risk a quarter of your users not being able to access mail with certain
high priority users having accounts replicated over more than one system.

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