`dkim-use-domain`: `<envelope | header>` ('default =' `envelope`)::

Whether to sign using the domain found in the header or the envelope.

`dkim_selector`: `<string>` ::

Default DKIM selector

`dkim_sign`: `<boolean>` ('default =' `0`)::

DKIM sign outbound mails with the configured Selector.

`dkim_sign_all_mail`: `<boolean>` ('default =' `0`)::

DKIM sign all outgoing mails irrespective of the Envelope From domain.

