Re: [exim] local_domains by dns

On Thu, Aug 26, 2021 at 3:24 PM Evgeniy Berdnikov via Exim-users <
exim-users@???> wrote:

>
> If somebody change MX to other host, he should think also how to handle
> multiple mailboxes (hosted on "old" place and on "new" one),
> and what to do with already stored mails.
>

Yes, this is something the client/customer and host/provider ideally should
be discussing before a change.

But if a domain holder changes the domain's DNS records to indicate that
delivery should happen at a different MX, it is not, ordinarily, reasonable
for a provider to override that.

There may be contractual requirements to override it, of course, but in
general, overriding DNS leads to confusion and (for the users)
"disappearing" e-mail.


> There is no such problem if locally submitted mails are always relayed
> via smarthost, even if they addressed to local users. To obey your scheme,
> smarthost should use only MXes for routing.
>
>
Ideally, all submitted e-mail should be routed on the basis of MX records
(or, in their absence, A records).

Additionally, you can (and in my humble opinion ought to) perform SPF and
DMARC policy lookups to determine whether your server is currently
authorized to send e-mail on behalf of the sending domain.
--
Jan