Re: [exim] Re-routing mail to the secondary MX server

On 2022-01-12 at 10:02:57 UTC-0500 (Wed, 12 Jan 2022 18:02:57 +0300)
Dmitriy Matrosov via Exim-users <sgf.dma@???>
is rumored to have said:

> Hi.
>
> Is it possible to re-route certain mails on the primary server (with
> lowest MX priority)
> to the secondary (the one with highest priority)?

No. That's not what secondary MXs are for.

> My use case is if the recipient is not found on the primary server,
> try to deliver a message to the secondary server (which is controlled
> by another person).

For a secondary MX to function safely it must have the same
understanding of the user namespace and filtering poliucy as the
primary. If you cannot do that, you should not have a secondary MX. The
main justifications for having a secondary MX at all are mostly
historical, dating back to when it was fairly common for routing to
break between IPs that could each talk to overlapping subsets of the
net. Unless you have chronic connectivity problems, a secondary MX is
not worth the complexities of setting it up and maintaining it well. A
secondary MX that you do not control is generally unworkable.


--
Bill Cole
bill@??? or billcole@???
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire