On Mon, 19 Jul 2021, Julian Bradfield via Exim-users wrote:
> I'm not sure of how to achieve the following aim.
>
> My setup is that I have two mail servers, call them FIRST and SECOND.
> Their exim configurations are almost identical, with one difference
> conditioned upon the presence of /etc/exim4/BACKUPMX .
>
> Normally, the MXes are FIRST with priority 10, and SECOND with
> priority 20.
> FIRST takes mail for the hosted domains and delivers it through
> procmail to home directories.
> SECOND accepts mail for the hosted domains and passes it to the
> dnslookup router for delivery - since FIRST has higher priority,
> dnslookup doesn't attempt to deliver to the local host.
>
> When, as now, my main server is at risk of disruption, I stop (and
> disable at boot) exim on FIRST, sync the home directories to SECOND,
> and restart exim on SECOND in main server mode. One DNS change to make
> the imap server address point to SECOND instead of FIRST, and I'm
> done.
>
> However, I want to be able to get messages generated on FIRST. If I
> start exim on FIRST in backup mode, then dnslookup will find FIRST as
> the first on the list, so I would have to set self=send to get
> delivery; but then it will just send to itself and loop.
>
> Is there a way I can achieve what I want *without* changing all the MX
> records for the hosted domains? (Or without rerouting to a special
> backup domain, or other such tricks.)
Can you put a router between the two existing routers that uses
driver = manualroute
in a similar way to the smarthost router in spec.txt 7.4 except
that you want to replace
domains = ! +local_domains
with whatever you use to detect mail that *should* be delivered locally ?
--
Andrew C. Aitchison Kendal, UK
andrew@???
