Hi Marc,
Thank you for your reply.
I did those alias but my problem is with Thunderbird that can’t get the certificate of the sending vhost server.
Looking at your reply: ThunderBird - Sieve not working?, I tried it as a partial solution by adding an exception for the certificate and now the DKIM for the mail from the secondary domaine shows the d=secondary-fqdn; which is what I want.
As said, this is a partial solution: but I would still like to have the real certificate from the sending server.
I didn’t take a walk yet… I am going to take it now…
Michel-André