Yeah, good point (re "the other way around"). That would be one of those "you can't win either way" cases we often have in IT.

Hartmut

On Thu 27 Oct 2022 at 08:14:35 -05:00, Alberto Abrao <alberto@abrao.net> wrote:

On 2022-10-27 05:34, Hartmut W Sager wrote:
> One quick thought does come to mind. Any chance you're using 2048-bit
> DKIM and that Yahoo can only work with 1024-bit DKIM? I encountered
> that in one of my study cases, where the receiving mail system can't
> verify.2048-bit DKIM.

Or the other way around. A few ESPs have been randomly reject 1024-bit
DKIM-signed messages, depending on the server where it lands on their end.

-Alberto