Problem DKIM Signature Did Not Verify

SYSTEM INFORMATION
OS type and version Ubuntu 20.4
Virtualmin version 7

I try to send email with my smtp server but when i test them i get this on mx toolbox deliverability check

Wether my dns are managed by Virtualmin or not. Can somebody help me?

It would help if you did inform us if you host your own dns server on your Virtualmin or If you had to copy and paste it to another provider.

Reason is most DNS providers don’t allow the " " syntax. Some will try to automatically remove them and not do a good job at it. As where BIND DNS allows them.

If this is the case? You need to make sure that all the " " (quotes) are removed along with any spaces.
Inside the key itself.