We keep the existing separate rate-limiting endpoint for existing
installations for now. The new policy/submission endpoint can handle
rate-limiting as well for new installations
The postfix configuration now contains the necessary minimum with
regards to the policy hooks. We need the extra hooks to collect
recipients.
To support delegation, the reject_sender_login_mismatch check has been
removed, so we rely on the access policy to check sender address
ownership.
Some adjustments were required to get the mailfilter to function again,
such as including a sender in the request.
The mailfilter does not currently deal with multiple recipients, so that
codepath doesn't really function yet.
kolab_policy_greylist and kolab_policy_spf are now just kolab_policy
(with arguments), since they function the same (they are not stateful
like kolab_policy_submission).