> On 18 Nov 2021, at 12:28 pm, Togan Muftuoglu <tog...@dinamizm.com> wrote:
>
> Thanks for the clarification. One more thing having the backup MX listed in
> the SPF records of the domain and opendkim signing the relayed mails does not
> break the validations in the primary MX when it receives mail from the backup,
> correct ?
Any receiving system that elects to use a backup MX must whitelist mail from
the backup MX:
* Not apply any SPF checks
* Not greylist
* Not reject messages other than to invalid recipients
--
Viktor.
