Send mails from own server with domain from third party server - DKIM

Luensche

Hello,

I have running mailcow-dockerized on my server. The server uses the domain abc.de, and I use mailboxes and aliases with xyz@abc.de.
I use this server to send mails from name@example.org, so a third party domain. Everything was okay till some weeks. The owner announced, that he needs a dkim public key from me to put it to the dns entry.

What is the best way to create and store a dkim key for the third party domain example.org?

esackbauer

I would say use a relay server for that domain, which is capable of signing the mails. The reason behind DKIM is that you are NOT able to sign mails if you do not own that 3rd party domain, or have access to their relay servers.