Re: [exim] Force authenticated local mail to use DNS

On 2016-02-03 18:51, Jasen Betts wrote:

> On 2016-02-03, mtrainer@??? <mtrainer@???> wrote:
>
>> Hi, Emails from our authenticated senders try to deliver locally if the domain is in our ldap directory even if the DNS MX record for the domain points externally. Is it possible in exim to make authenticated emails use the DNS MX instead of just delivering internally if the domain is in our ldap directory. This of course can't break normal incoming emails. The contents of our routers.conf file is below. Some advice on how to solve this problem would be greatly appreciated.
>
> yes, you'll have to remove those domains from the "local_domains" list
>
> -- _(ツ)_

Hi Jasen,

Thanks for the reply. In an ideal world it would be as simple as that.
The problem is that customers just change their mx and leave their
existing mail / domains on our system. It is difficult to detect when
customers change their mx especially when we have 70,000+ domains. Also
some of our domains use spam filters so we would have to exclude them
from being removed. Also customers may need time to migrate their mail
elsewhere. It is alll very messy, so we can't just automatically remove
the domains and emails immediately after they change the MX externally.

This problem only affects emails from our internal mail domains. These
users send mail via authenticated smtp sessions via our mta's running
exim. I was hoping there would be a more elegant approach using exim
routers to make the emails from authenticated sender do a DNS check and
if it is internal then check the list of local domains before sending
mail internally. If the DNS points externally then the mail should go to
the external destination thus solving the problem.

Could someone knowledgeable about exim routers let me know if there is
possible?

Thanks

Murray