On Mon, 28 Oct 2019, Christian K via Exim-users wrote:
> Hi,
>
> I?m trying to sign all mails with DKIM from all subdomains of certain
> domains with the key of the ?main? dkim domain. Or in other words I
> want to find the dkim fallback domain to know which key I need to use
> for signing.
>
> Some examples for what domains I need to find the key for:
> foo.example.com -> example.com
> foo.bar.example.com -> example.com
> foo.example.co.uk -> example.co.uk
> foo.bar.example.co.uk -> example.co.uk
>
> I thought about using some regex substitution but with double domains
> it?s not that?s easy.
>
> Is there another way to achieve this?
The Public Suffix list
https://publicsuffix.org/
may help you determine when you need "double domains".
--
Andrew C. Aitchison Kendal, UK
andrew@???
