I recon you could do it by setting a real big value on the mx record of
the secondary box. Set up the server so that any mail (should be almost
never) it receives are fired off back at your primary as well as being
locally delivered....
This way the secondary box grabs mail if the primary is down.
When the primary comes up, the messages are fired off back at the
primary (assuming it hasn't been down for too long).
This means users may get some messages twice.
The record for mail.whatever.com may have to be changed manually...(or
maybe the same thing as with the mx records could be done) so set time
to live at like 15mins.
Optionally if you wanted mail not downloaded to be on the secondary, a
regular (i.e. every 10mins or so) rsync over ssh of the local mail
directories from the primary to the secondary could be done...
John Ferlito wrote:
>
> On Tue, Oct 24, 2000 at 10:07:23AM +1000, Marshall, Joshua wrote:
> > Does anyone know of a good method to make an email system redundant, so
> > that if one server goes down (power loss, network loss etc) the users
> > can still retrieve and send emails ?
>
> Send emails shouldn't be too much of a problem. You can setup
> something like heartbeat todo ip takeover and pretend to be the outgoing
> mail server for a bit. Recieving is really difficult though. Almost
> impossible because you would end up with mail spools in two different
> places when the other box comes up and you would have to find a pop
> client that would deal with that. Unless you have a third box which NFS
> servers /var/spool/mail then you could setup both boxes as primary MX's
> and allow either of them to deliver. But you need to make sure you get
> locking right.
>
> --
> John
>
> The difference between a good man and a bad one is the
> choice of cause - William James
>
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