New mail server setup

Steve Bertrand steve at
Thu Sep 17 12:49:46 UTC 2009

Michael K. Smith - Adhost wrote:

>>> Steve Bertrand wrote:
>>>> If anyone has a setup that has redundancy for their IMAP/POP
>> services,
>>>> and a method to keep the changing data relatively up-to-date, I'd
>> love
>>>> to hear about it.

[ big snip ]

> Another approach would be a cluster of Postfix servers and Dovecot
> servers behind PF load balancers.  We have 3 "POP" servers (IMAP/POP), 9
> Mail Servers, 2 Defer servers and 5 Filter servers that process over 20
> million messages a day without a blip.  We can take individual servers
> out of the pool for maintenance, etc.  Everything is fed to a set of
> redundant NAS for the data storage and common configuration files.

Thanks Mike,

I'm interested to learn a little more about your setup. I was going to
take it off-list, but if you can provide some further details, it would
probably add long-term value to keep it here.

So, a couple of questions:

- can your PF load balancers 'sense' when one of the Postfix/Dovecot
units are down, or is this a manual change in config to prevent any
time-out conditions?

I like this load balancer idea. In my environment, it would be trivial
to set up a couple of them, throw Quagga on them, and integrate them
directly into our iBGP setup. On the other side, I could use VRRP or the
like to ensure redundancy from front to back.

- do the Postfix/Dovecot servers communicate with each other, or are
they simply stand-alone units that don't know/care that they have other
peers helping with the workload?

- are your filter servers in front of, or behind the load balancers
(iow, is all of your inbound email passed through the balancers, and
then filtered/processed/delivered in behind them)?

- how do all of the pieces communicate with the NAS...NFS?

- could you share a small snip of your PF config in relation to
load-balancing, so I can get a bit of a better understanding config-wise
on how that piece hangs together? (I've never used PF, only IFPW ;)

Thanks, and regards,


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