Re: [Exim] Some questions

> If the first server goes down, mailservers from the net will contact
> your secondary MX, it handles as much as it can and queues mails for the
> first server until it can be reached again. It will recognize that the
> first server is down simply by being unable to reach it. Where's the
> problem?

That's how I understand it as well, and to my understanding how it should
work. However, what is required on the secondary MX machine to let it know
to queue and re-route the domains?

A domain for which the secondary MX is there, the domain cannot be specified
in local_domains because the secondary MX will not process any deliveries
for the domain, so what exactly is needed here?

The manual "re-route" I get and understand, I can process it with a simple
router, ex:
backup_MX:
domains = backupdomain.com
driver = domainlist
transport = remote_smtp
route_list = * mailserver.backupdomain.com byname
self = fail_soft

I'm sure I'll need something else to tell exim to accept messages for
backupdomain.com however, because it is not specified in local_domains
(which it cannot be). Would this be a entry for relay_domains on the
secondary servers then?