DKIM issues

Bonjour !

I have these issues with DKIM :

dkim-filter[2582]: 2441AAC100: key retrieval failed
dkim-filter[2582]: AB549AC100: no signature data

they come very often in my mail.log, and I get puzzled.

Did I do something wrong ?

Since DKIM is no longer supported,
is it a drag to deactivate it and install OPEN DKIM instead ?

Thank you for the time you spent considering this !

Anyone ?